The Messier Pro

Why "What Is Up" Has Been Down ...

2011-12-05T22:17:00.001-06:00

.....I have not had a post go up since September for a couple of reasons that I wanted to share with you (though this is an aberration - the whole point of this blog is the sky, not me). At the end of September, I had a bicycle accident that resulted in a hairline fracture of the S4 vertebra, which led to a couple of weeks of intense pain, which was much worse at night. At the same time, my work situation became extremely negative, a full-fledged cautionary tale about the total lack of protection the worker has without a union.

.....In any event, the continuing evolution of a look for the monthly star map is coming very soon, and I will also begin looking toward the transit of Venus across the face of the Sun on June 5th, 2012. It will be possible to actually watch the disk of the planet Venus cross the Sun. This is definitely something to try to see, since we won't be able to see this happen again until December of 2117!

The September Sky

2011-09-16T15:23:00.001-05:00

.....This blog has not been updated in an uncharacteristically long stretch because of personal pressures with the beginning of a new school year, and my move to a new house, with an actual backyard - a backyard that has a line-of-sight to zero streetlights, instead of the eight at the apartment! I hope that I don't become what I criticized (in backyard astronomers who assume everyone has good skies) now that my situation has improved! (I am am in the city proper, though not a bright part of not a big city.)

.....Halfway through the month, here are the stars for September. As is usual for this first pass, the constellation covered are in blue, tending to the west, while up-and-coming constellations have the eastern sky in red.

.....The limiting magnitude for this map is fourth magnitude, which could still be fairly optimistic for a lot of suburban and urban viewing. When I did this, I also had to redraw a number of constellation patterns, as there are some constellations arranged in ways to make the figure hopefully look weakly, vaguely, as their namesakes, but squeezing this in often used faint stars that are hard to see under bright skies.

....Ursa Minor, the Little Dipper, is high on this list. Only three of the seven stars can reliably be seen, so many, many people looking for the North Star by using the Little Dipper identify something else. Pisces, wrapped around Pegasus, is another faint constellation with only a few bright stars. If we overlay this map onto stars down to the limit of visibility, we find the patterns our backyard astronomy books promise us, but buried in an embarrassment of riches.

.....Locating constellations in September should start with the Summer Triangle. The Triangle is at its zenith, the highest point in the sky,connecting the brightest stars in Aquila, Lyra, and Cygnus. Rising in the East is the Great Square of Pegasus, a dimmer figure in a dimmer part of the sky. You will be well rewarding for wandering out into the summer sky: the nights are cool enough to keep down the humidity (and hopefully the mosquitoes), and the last views of the summer Milky Way are visible in the southwest, the Milky Way itself passes directly above us. Good Luck!

Eagles

2011-08-22T21:06:00.002-05:00

.....The second constellation joined by the Summer Triangle is Aquila, the Eagle. (We move east in our examination of the constellations, and we have covered enough now to see blue constellations to the south and west, and red, or "not yet covered" mostly to the west.) Altair, the bright star bracketed by fainter stars to the northwest and southeast, is the bottom star of the Summer Triangle, and the brightest star in Aquila. Altair is also fairly close to Earth. The light that you see tonight left on November 15th, 1994 (plus or minus a month).

.....Here is the "Binocular View" of most of Aquila, with the names of the named stars included. This includes some very long names for very faint stars. I refer to Deneb el Okab Borealis/Australis, or "The tail of the eagle north/south". (The Arabs clearly visualized this image differently than I have drawn it here.) Deneb el Okab Borealis has a visual magnitude of 4.00, making this one of the faintest named stars we have covered.

.....The next step, on the next go 'round, would be to have more detailed maps of the cool clusters, nebulae, galaxies, etc., to be found in Aquila especially since the summer Milky Way passes through the constellation ... but there are none to be easily found. There are no Messier Objects, no Caldwell Objects (a list constructed by Sir Patrick Caldwell-Moore to include material Messier didn't), and the Sky Atlas 2000.0 Companion (to one of the most prominent star atlases extant) has numerous objects, with notations like "extremely faint", "not well detached", "appears stellar". All of the cool thing in Aquila seemed to have slipped to bordering constellations. (Sagitta, the faint constellation above Aquila, has three cool deep-sky objects.)

.....So let's digress into eagles in general. There are a lot of stars named "Something, something eagle", because, well, eagles are cool. Eurasia has about fifty types of eagles, while North America has two. This was unfortunate, as the first country to become independent in North America (the United States of America) took the bald eagle as its symbol, Mexico put the golden eagle on its flag, and Canada got ... the loon.

.....Countries all over the world have used an eagle as a symbol. This makes sense. When you see an eagle on a flag, seal, official souvenir baseball cap, you think, "I wonder which aspect they are going for: freedom, vision, heck, even apex predator?"

.....As opposed to the alarmingly common two-headed eagle, which only brings to mind the question, "How many hit points does it have?" (And yes, out of all my choices, I am choosing to pick on Austria-Hungary, a nation that has been defunct for coming up on a century. You never know what people are going to get peeved over.

.....Let's sum up. Using the symbol of an eagle (one head, left), you get this. Use the two-headed eagle (right), you get, "Ahhhh! AAAHHHH! Someone protect the CHILDREN!"

Sagittarius, or the Effort A Culture Must Exert If It Does Not Have Tea

2011-08-18T21:23:00.002-05:00

.....One of the best summer constellations is Sagittarius the archer. Its central figure made of fairly bright stars, and it is filled with deep sky objects, open clusters, globular clusters, and nebulosity. The only downside to Sagittarius is that it is low in the sky (in the Northern Hemisphere), so Sagittarius is only visible from late July to late September, but when it is visible, Sagittarius is a visual feast. If you have a dark sky, the summer Milky Way appears to split between Sagittarius and Scorpius (due to a tremendous amount of non-luminous gas and dust between us and the center of the Milky Way). If you do not have dark skies, this is still a very rich constellation for binoculars, especially in the central figure of the constellation.

.....Let's take a look at that now. The stick figure above is supposed to represent a centaur holding a bow, prepared to take out Scorpius execution-style. This obviously didn't work, because Scorpius is still there, and Sagitta (the constellation of the arrow, as opposed to the constellation of the archer) is north of both constellations, having apparently bounced off of the natural armor of Scorpius.

.....Far easier to visualize is a more modern asterism , the Teapot. Drawn below, the bright stars of Sagittarius' center form an excellent teapot, with stars like Nunki and Ascella as part of the handle, Kaus Borealis as the top of the dome, and Kaus Media, Alnasl, and Kaus Australis as the spout. This may still involve some scorpion hate, but it strikes me as far more effective to go after a scorpion with boiling liquid than an arrow much smaller than the scorpion. Plus, really, scorpions? %#@& those guys.

.....This brings up a couple of additional points. Sagittarius seems to have a number of named stars, but scores low points for originality. What's up with that? As it turns out, "Kaus" is Arabic for "bow", so three of these stars represent the bow. (In that case, if someone could give me the Arabic word for "teapot", then I could rename seven stars in one fell swoop.) "Arkab" is Arabic for "hamstring".

.....As an aside, the US Navy commissioned a cargo vessel named "Arkab", named after the star(s) that conveyed cargo to Pacific bases during World War II, traveling more than 60,000 miles. Despite Arkab being Beta Sagittarii (implying that at least one of the Arkabs should be the second-brightest star in Sagittarius), the Navy ship is the coolest fact about Arkab. Arkab, and Rukbat (Alpha Sagittarii) are actually quite dim, nowhere near being the brightest stars. In many other constellations, the star "Alpha The-What-The-Heck-Ever-i" isn't the brightest, but it is usually close, or part of a clear pattern (as in the Big Dipper). This time it just makes no freaking sense.

.....One the "Binocular View" close-up of the Teapot, a number of Messier Objects are listed. Even in a pair of binoculars, the globular cluster M22, and the Lagoon Nebula (M8) are obvious, and wonderful targets.

The New Standard In Charts!

2011-08-17T09:24:00.000-05:00

.....I have worked at this for some time, and I have now settled on a system of chart scales. (I had intended to let each chart be at what seemed like an appropriate size scale for that individual constellation, but the advantages of using a standard set of scaled views are pretty appealing. Some constellations, such as Draco or the combined Ophiuchus and Serpens, naturally fill a field of view thirty degrees in radius. (At arms length, both hands held together - or, as I now notice, your right hand and a friend's right hand - span thirty degrees in the sky.) For smaller constellations such as Lyra (shown below), the "Constellation View" shows the constellation in context with other constellations around them, which serves (I hope) to make them easier to find. On the "Constellation View" charts, the faintest stars are sixth magnitude, the theoretical lower limit of visibility for the average person with a dark, moonless, sky.

.....Smaller constellations should still get a view of the whole constellation, and larger constellations could be served by higher resolution views of interesting areas. These maps are "Binocular View" maps, making the implicit assumption that this closer view serves to let use find interesting areas, and search through them. For this reason, the faintest magnitude plotted on the chart is eighth magnitude - too faint for the unaided eye (although perhaps I shouldn't be trying to avoid getting Google hits for the word "naked" - a hit is a hit, after all), but visible in binoculars.

.....The final goal for this blog is to help the reader (especially the reader relatively new to observing, or observing through light pollution) find interesting telescopic objects. This brings us to "Finder View", with a radius of five degrees, and showing the amount of sky typically visible through a "standard" small telescope. These will usually be used to help the gentle reader find cool things to look at, and the faintest star going down to tenth magnitude, bright enough to be fairly easily seen through a small telescope.

.....The map above zooms in on one of the easiest to find deep-sky objects, the Ring Nebula (M57), a planetary nebula (the swelling former outer part of a star, dissolving into space). In a small telescope, this appears as a fuzzy bright doughnut of light.

Sagittarius, or the Effort A Culture Must Exert If It Does Not Have Tea

2011-08-16T18:47:00.000-05:00

Names Out the Wazoo

2011-08-15T15:58:00.001-05:00

.....The name of this constellation is more widely recognizable through Harry Potter than through astronomy awareness, but that might not be unfair.

,,,,,The constellation Draco the dragon is a northern circumpolar constellation. For much of the northern hemisphere, Draco is above the horizon for all of the year. North of the Mason-Dixon line, Draco is always in the sky, winding part of its length between the DIppers. Well, if this is the case, why is Draco so much less familiar? The short answer is that Draco, while large, has no bright stars. The brightest star in Draco has a visual magnitude of 2.23, or the 69th brightest star in the sky. Draco's primary claim to fame is that Thuban, one of its stars, is periodically the North Star. Thuban's last pass at glory came during the construction of the pyramids (giving us about twenty-two thousand years until its next turn at the pole)

.....Draco is quite a large constellation, filling our starting placement map. No zooming will be necessary. One might note that while Draco has no truly bright stars, its has a number of named stars. This seems strange at first blush, so let's conjecture why this might be...

.....First, when many of our constellations were being named (or at least getting the names that would stick), Draco contained the North Celestial Pole, with the entire sky appearing to rotate around Thuban the way that the sky now appears to rotate around Polaris. This naturally made Draco an important constellation, so its stars were more likely to receive names. But ask yourself this question: Why did stars receive individual names in the first place? Imagine yourself standing outside, looking up at the stars with at least one friend (unless you are actually doing this, in which case I salute you, and hope that your presumably mobile device has a dimming feature). Pick a star. Now, how would describe which star you had picked to your friend? If your star was the brightest in a given area, you might describe it that way, and if it was not, there is an excellent chance that you used that bright star as part of your directions. If we start with a set of named stars, then we can cut out a lot of the uncertainty right from the get-go: "It's that star right below Vega," you might say (if it happened to be that star). Now, if you were looking a Draco, Draco is (a) very large, and (b) low on bright stars. that could lead to a number of stars in Draco getting names, just to have a starting point telling one not terribly bright star from another.

.....Speaking of names, the name Draco is probably more recognizable as Harry Potter's classmate and frequent antagonist from the eponymous series. Readers (as opposed to movie viewers) may have recognized a number of star and constellation names, mostly in the Black and Malfoy families. (What, did an astronomer cut J. K. Rowling off on her way to the coffee shop one day?) Here are the names used, and where in the sky they can be found:

Andromeda Tonks, nee Black, the mother of Nymphadora Tonks: Andromeda is a fall constellation, now visible on the eastern horizon once night has fully fallen.

Alphard Black :The son of Pollux Black and the uncle of Sirius Black

Arcturus Black, patron of Sirius Black: Arcturus is the brightest star in the constellation of

Boötes.

Bellatrix Lestrange, nee Black, major villain: Bellatrix is one of the bright stars that form the winter constellation of Orion. Bellatrix (Latin for "female warrior") is the western shoulder of Orion.

Cassiopeia Black: Cassiopeia is a circumpolar constellation for much of the northern hemisphere, most prominent in the fall sky, appearing as an "M" or a "W", depending on what side of the Mississippi River you're on . (At least around here. :) )

Cygnus Black: Cygnus (aka the northern cross, containing the star Deneb) is a major summer constellation.

Pollux Black: Pollux is a bright star in the winter constellation of Gemini.

Regulus Arcturus Black: Regulus is the brightest star in the constellation of Leo.

Sirius Black: Sirius is the brightest star as seen from Earth (fine, barring the Sun, for the pedants out there), and is located in the winter constellation of Canis Major.

Callidora, Cedrella, Charis, Dorea, Elladora, Hesper, Isla, Lucretia, Marius, Phineas: These are not star names. Ms. Rowling apparently had other ideas, or ran out of star names that she liked. (Oh come on! What about "Microscopium Black", or "Aldhibain Black"? That's a missed opportunity right there!)

.....Draco also takes part in a giant summer man-versus-reptile showdown. As intimated here, and more visible on the August star map, Hercules is stomping in Draco's head, back-to-back with Ophiuchus while Ophiuchus is wrestling with Serpens. Thankfully, the constellations were derived thousands of years before the advent of Freudian analysis.

.....Also, wow, this sould have been much more timely if I had posted it a month ago...

Lyre Solo (or Solo Lyre)

2011-08-13T10:59:00.002-05:00

.....The constellation of Lyra is small, but it holds one corner of the Summer Triangle, and the fifth brightest star in the sky - the second brightest star in the northern sky. Lyra contains the star Vega noteworthy because this constellation, unlike some others like Scorpius, is quite high in the sky in the northern hemisphere, passing directly overhead of the southern United States. (Spookily, Vega passes almost directly overhead of Washington D.C..)

.....While this is something that I have done for the last few constellations, I have a more well-defined standard format for how constellations are presented. The first map shows the sky, centered on the constellation in question, with a radius of thirty degrees. For all but the largest constellations (and Lyra is kind of small), this will show a number of bordering constellations. This gives us a standard starting point, and helps us find the constellation in the sky. (In the case of Lyra, this helps us find other constellations as Vega is pretty hard to miss.)

.....Zooming in on Lyra (this map has a radius of eight degrees, we see Lyra as it is usually portrayed, a triangle of stars sharing a corner with a parallelogram.

.....Looking up on a summer night, Lyra seems quite and serene. Less than a dozen stars, one bright, but otherwise quite. Actually, Lyra has some notable weirdness to its stars. Vega is larger and more luminous than the Sun, but its brightness in the sky is due to its closeness. Vega is only a little more than 25 light years away, so the light that you can see from Vega tonight left in late April of 1986. Being close, Vega is relatively easy to study, and astronomers have fond a massive disk of gas and dust around Vega, with irregularities that might indicate the presence of planets. Weirder than this is the other star only in the "triangle" of Lyra, designated Epsilon Lyrae. Through binoculars (and on the second map), this star is revealed as a pair of stars close together in the sky. This is no coincidence; those are actually orbiting a common center of mass - but it get stranger. Looking through a telescope with high magnification on a clear, steady night, each of these stars is revealed as a double star in their own right, so this is also called the Double-Double, four stars orbiting in pairs that orbit each other.

.....Even weirder is Sheliak, or Beta Lyrae. Sheliak is 882 light years away, so for the light reaching us (from 1129, the year of the Council of Troyes franchising the Knights Templar - let's see what Dan Brown does with that) to still make Sheliak the second brightest star in constellation must be something outstanding indeed! Sheliak is also a double star; nothing strange in this, most stars orbit in pairs (or more). In Beta Lyrae's case, the two stars are so close together that the gravity of each star distorts the other, and material is pulled off of one towards the other. These stars are orbiting so quickly that as the stream of gas moves toward the hotter star, it misses the star, building up into a disk. Even this disk overflows, with material escaping into space from the poles, and leaking out from the opposite side of the accretion disk

.....Because Lyra is a fairly tiny constellation, I have included two telescope objects on this map as well. This kind of skips ahead in my plans, since I intend to discuss these objects on my next tour of the constellations, but if you have even the smallest of telescopes, the object M57, aka the Ring Nebula, is straightforward to find between Sulafat and Sheliak. (When I was in seventh and eighth grade, my backyard telescope had a lens actually slightly smaller than the human eye, and a tripod with legs six inches long that I would need to balance on the posts of a chain-link fence. I could find Jupiter, Saturn, the Orion Nebula, the Andromeda Galaxy ... and the Ring. The other deep-sky object is M56, a globular cluster that is one of literally dozens of globular clusters that can be seen in the summer sky.

.....As a last point, I have previously discussed how the north star can be hard to find because the constellation it is in is so faint. Also, there are a number of people who (if pressed) will claim that the North Star is the brightest star in the sky. (There is at least one who simply tongue-in-cheek defines the North Star this way be fiat. Her car has GPS, so navigating by the stars is not a daily requirement.) The North Star is not the brightest, but due to the Earth's long, slow 26,000 year wobble on its axis, if you wait about twelve thousand years, you (or your head in a jar) can see Vega as the star closest to the pole.

The August Sky

2011-08-12T09:04:00.001-05:00

.....August is one of the best observing months of the year. The nights are starting to get a bit longer (still cursed by Daylight Savings Time), and the Summer Milky Way, including the center of the galaxy, moves across the center of the sky from Perseus in the northeast, through Cassiopeia, Cepheus, Cygnus, Aquila, Sagittarius and Scorpius. While I have not yet discussed many of the constellations with the Milky Way, just wandering through this section of the Milky Way with binoculars is wonderfully rewarding.

.....As before, constellations that have been covered in the blog are shown in blue (Ursa Major, Ursa Minor, Boötes, Libra, Corona Borealis, Hercules, Ophiuchus and Serpens, and Scorpius), with other constellations in red. Saturn is being lost in the west, so if you want to observe Saturn, you'll have to do it in evening twilight, though if you look east starting at about 1 AM, you can see Jupiter rising. As always, constellations we have yet to cover are in red.

.....August is most notable for the Perseid meteor shower (on which more later). In short, during the first part of the month, meteors will be more common, many of them seeming to track from the northeast and the constellation Perseus. Try to squeeze out meteor observing early, though, because while the meteor shower peaks on the night of August 11th, so does the full Moon.

The Best Meteors of the Year ... Darn It!

2011-08-11T14:43:00.002-05:00

.....The most reliable meteor shower of the year is the Perseid meteor shower, usually peaking on the night between August 11th and August 12th. In younger years, this was the one time during the year that I could get the whole family as interested in astronomy as I was, a situation that I found was pretty common. In recent years, I have often held public observing sessions, which have turned out really well, as there is no bottleneck at the telescopes; meteor observing is laying back, getting comfortable, and trying to keep as much of the sky as possible visible to see shooting stars. Easy to set up, and enjoyed by all.

.....I'm not doing that this year.

.....Let me explain why. Every dark, moonless night not dominated by city lights, we can expect to see a few shooting stars per hour, flashing randomly across the sky. These typically come from one of three sources: Leftover bits of flotsam and jetsam that have been floating around the solar system for the last five and a half billion years (cool), little bits that have been boiled off of comets as they passed around the Sun (also cool), or nuts/bolts/heat shields/tool boxes that have come off of space craft and are crashing back down to Earth (less cool).

.....Each time a comet passes through the inner solar system, if it still has much of its original ice, that ice will boil off, taking some dust pebbles with it, and the ice will reflect sunlight, resulting in the bright coma and tail. What happens to this once the comet goes back to the outer reaches of the solar system? Nothing. That comet rubble stays in orbit, resulting in the comet's orbit eventually becoming a dusty tube of gunk around the Sun. If the Earth should pass through this gunk, then when the particles hit the Earth's atmosphere they will light up from the heat of friction generated from going from a temperature of less than three hundred degrees below zero (Fahrenheit) to thousands of degrees. Since all of these meteors are coming from the same general area in space, they will appear to come from the same general area of the sky, meaning that the meteors will all seem to radiate out from the same point. (Called, reasonably enough, the "radiant".)

.....Each August, the Earth passes through the remnant trail of the comet Swift-Tuttle, generating the Perseid meteor shower because the radiant of the meteors (the dotted circle in the image below) is in the constellation of Perseus. Meteor showers do not require a telescope or binoculars; just go outside and look (in this case to the northeast, especially after midnight).

.....A lot of this is part of the standard run up to a meteor shower. What makes this year different is that the meteor shower peaks only about a day before the full Moon. Looking at different sources, the number of meteors per hour for the Perseid Meteor shower is usually given as a number between 60 and 120. (Wow!) Now let's look at that as the sky gets brighter due to the Moon. Even if we take the most generous version, that considers that we can see all the way down to our eyes limit. With the bright Moon, we can't. With an interfering Moon, even if we could see down to fifth magnitude (as opposed to sixth magnitude, our limit), we would go from 120 down to about 46. The full Moon is much more limiting than this, however. Even if we assume a third magnitude limit, we're down to about seven. Per hour. With any bad or humid air, this could limit us to second magnitude (maybe three meteors an hour, if we're lucky), or first (maybe three meteors every four hours). This is enough of a enthusiasm-killer that it's better to look to next year, when the moon will be much less troublesome.

.....Looking for Perseids can still be done in the nights leading up to Thursday night, but the Moon will drown out most of them. Here is a map of the northeastern part of the sky on Thursday at about midnight.

The Best Meteors of the Year ... Darn It!

2011-08-08T19:00:00.003-05:00

Why I hate Microsoft's Spellchecker

2011-07-28T13:30:00.001-05:00

.....The constellation of Scorpius (the Scorpion) appears in the southern sky at this time each year, as seen from the Northern Hemisphere. There are several myth explaining this constellation; of them, one holds that this is the scorpion that killed Orion the Hunter, thus explaining why the two constellations can never be seen in the sky together. (There is more than one story concerning the death of Orion, so this may explain why Aesculapius is credited with bringing Orion back back from the dead to be killed in more interesting ways by the gods. I've had days that felt like that.) A different myth from Hawai'i explains that this constellation is Maui's fishhook, which got caught on the bottom of the ocean and dredged up the Hawaiian Islands.

.....There have some good news, and I have some bad news ... oh, what the heck, I'll start out with the good news, everybody likes good news ... Scorpius has a number of bright stars, and it's basic pattern (a scraggly line) is fairly easy to follow. Furthermore, as we will see on our next cycle through the constellations, Scorpius has a number of bright star clusters, and some of them look very attractive through binoculars. (Two bright open clusters can be found by looking just to the northeast (up and left, on the map) of Shaula and Girtab. these are labeled as M6 and M7, and they are quite nice sights in binoculars or a telescope. This is not a surprise, as the summer Milky Way goes through Scorpius and Sagittarius, and covers most of these constellations. In fact, on this map the center of our galaxy is about 30,00 light years away, in a direction just north of M6.

.....The map below shows Scorpius on our "standard" sized maps, with a radius of 30 degrees (where the angular distance across the sky from the end of a fully extended pinky to the end of a fully ectended thumb, held at arm's length, is about 15 degrees.

.....Let's zoom in a bit (the radius of this image is 20 degrees) so that the traditional star names clearly refer to their associated stars, and we get a bit of a closer view.

.....The bad news is that Scorpius is located far to the south in the sky. In the northern hemisphere, Scorpius spends less time above the horizon, rising in the southeast (instead of the east), and setting in the southwest. On the chart below, I am showing the approximate horizon for Scorpius, at its very highest, for a selection of American cities. (If you don't live in one of these cities, go by latitude.) For areas that correspond to the northern United States (Philadelphia is at about the same latitude as Beijing, and is actually south of Istanbul), Scorpius is only fully above the horizon for a brief time. Add to this that this map assumes an uncluttered southern horizon, so that any trees, hills, or Pump 'N Munches will interfere with that, and that when looking that low on the horizon you are looking through more than five times as much, wobbly, humid, dusty air as when you look straight up, observing Scorpius can feel like you are trying to do so from the bottom of a swimming pool.

.....So if you are living in the continental United States, or at comparative latitudes (in Asia, the horizon of Karachi, Pakistan would be roughly equivalent to Miami), then the existence of the stars in the highlighted area will simply have to be taken at my word.

.....Now if you have gotten your knowledge of the sky from a newspaper column across from Family Circus, or if you are a spellchecking program, you may have been subconsciously changing the name of the constellation to "Scorpio" but that's not its name. Spread the word, okay?

Snakes! Why'd It Have To Be Snakes?

2011-07-21T22:23:00.000-05:00

.....One of the largest constellations in the summer sky is actually two constellations. In another sense, it could be thought of three constellations. Technically, the constellation of Ophiuchus is the Serpent Bearer, and the constellation of Serpens, the serpent that he his carrying/wrestling with. Here is a map of the constellation:

.....And below is the representation of this constellation as Johann Bayer drew it in the star atlas Uranometria, in case my description of the constellation didn't make sense to you ...

When illustrating a figure named "man wrestling giant serpent" it is a wise artistic move NOT to show from the front.

.....which would be reasonable, as while most constellations at least make some sort of surface level of sense (the hunter, the scorpion, the northern crown, the swan, ...) what the heck is up with "the guy holding snake"? When does that make sense?

.....Here's where the problem comes in. Suppose that it is not a good night, and the limiting magnitude is 2.00. (This would be a really bad night in the country, but if you live somewhere with a lot of streetlights, this could come into play as a bright night or if that part of the sky is over some of these lights.) In that case, you see nothing in this area.

.....With a little better sky, and a limiting magnitude of 4.00, at least the "house" shape of Ophiuchus shows up. Serpens is largely invisible yet, and since there are no real patterns in Serpens, just a "scraggly line of stars", this constellation is still invisible. (On our next pass through the constellations, next year, this does at least give us bright stars to allow us to start finding all of the bright globular clusters in these two constellations.)

.....We need to be able to see all the way down to fifth magnitude in order to make out the patterns of Ophiuchus and Serpens. On the map at the beginning, for this constellation I had to show stars down to sixth magnitude in order for the patterns to be apparent.

.....All of this can distract from the basic oddness of the constellations themselves. I'm not referring to Serpens being split in half, with Serpens Caput (the head) and Serpens Cauda (the tail), but the story of the constellation itself. The constellation group seems to be so old that there is not "a" story associated with the stars, but a "well, I guess it means..." explaining the large pattern of a guy wrestling with a snake. The most common explanation is that the star group represents Aesculapius, the son of Apollo who became so proficient at medicine that he could bring the dead back to life. (One of his subjects was Orion the Hunter, or this could be a Classical retconn to account for the two different legends of Orion's death.) This, as one might guess, is one of the fast ways to land you on the gods' &^%$ list, so he was immediately struck down and placed in the heavens. The serpent has represented the medical profession (including the intertwined serpents of the Caduceus) because the ancients saw the snake shedding its skin and got the idea that the snake could therefore regenerate its way to immortality, a feat actually reserved for Timelords. There are many, many other myths that have been attached to these stars from " Hey, maybe it's Izhdubar opposing Tiamat" to "Hey, let's change it to Saint Benedict among the thorns".

.....I was going to now try and see if I could find some other pattern among the stars that might be more recognizable than, well, something that no one has recognized, when Anne Marie walked behind me and asked, "Which constellation is the frog?"

.....Frog? What the heck are you talking ...

.....Well, blast.

.....Lastly Ophiuchus is actually the thirteenth constellation of the Zodiac, as the path of the Sun crosses that little leg sticking out of the bottom. Ophiuchus actually contains the Sun from November 30th until December 17th. Scorpius only contains the Sun from November 22nd until November 29th. (Yes, neither of these match up with what the columns in the newspapers say: those are based entirely on the Babylonian religion of 2500 years ago, and have slightly less reliability than, say, Charlie Sheen.

The July Sky

2011-07-12T21:11:00.001-05:00

.....The was a bit of a blip posting this, so here is the correct version.

.....Below is shown an image of the night sky as it is at ten PM in early July (corresponding to nine PM in mid-July, and eight PM by late July. We can now start to see how the sky changes over time by comparing the sky in July with the sky in June (also shown below).

.....As before, I have included constellations that have already been discussed (Boötes, Ursa Major, Libra, Ursa Minor, and the asterism of the Summer Triangle) as well as some constellations that will be coming soon, such as Ophuichus and Serpens, Scorpius, Sagittarius, Lyra, Aquila, and Cygnus). Note that on the maps below, the points of the compass are shown as on the maps above. To see these constellations, take your computer (or print out the map, totally your choice) and turn it so that the labeled north (south, east, west, whatever) is at the bottom of the map when you are looking north (south, east, west, whatever.

.....The summer sky can illustrate a couple of different points. The map below shows all stars theoretically visible, all the way down to sixth magnitude. There are two reasons why I don't use this map for my basic sky map; sadly, the vast majority of people don't get to see the sky like this (I did, last week, and I'll be writing about that tomorrow), and if you did see the sky like this, it might well overwhelm even a fairly experienced suburban skywatcher. Also on the map below, you might note that there are more stars in the eastern sky than the western sky, and that there almost seems to be a band going from the south to the northeast. This is the summer Milky Way with the center of our galaxy between Scorpius and Sagittarius (and then another 30,000 light years), so hopefully this makes sense.

.....This map assumes that the reader can see stars of fifth magnitude or brighter. This is still wildly optimistic for most people, but as you will see, I kind of need to go to this level in order for the patterns as generally associated with the constellations to make any sense.

.....This map shows the sky to a limiting magnitude of fourth magnitude (remember that the lower the number, the brighter the star). Holes start to appear in the constellation patterns.

.....If the sky is cloudy or bright enough that nothing fainter than third magnitude can be seen, then only the larger patterns (such as the Summer Triangle) can be seen.

.....Now that only second magnitude stars or brighter are shown, then only the brightest stars appear, but it is still enough to allow you to orient yourself.

.....If first magnitude stars are visible, one might wish to go back inside and expand your mind or hang out with loved ones, or, at this point, just watch some TV.

.....Finally, it could be completely cloudy:

Libra (Reprsie)

2011-06-23T10:11:00.002-05:00

.....Libra is the first of the constellations along the Zodiac that I have written about here. What is the Zodiac? The ecliptic is the path that the Sun takes through the sky, and the planets all stay within 7° of this line (If we skip Mercury, all the planets are within half this distance of the ecliptic). The ecliptic passes through twelve constellations (traditionally; as the constellations were given boundaries by the International Astronomical Union in 1930 the ecliptic passes through thirteen constellations), and these constellations are the Zodiac. Besides being the only zodiacal constellation with no bright deep sky objects, Libra is also the only zodiacal constellation named after an inanimate object.

.....Our constellations can be traced back to the forty-eight the Greeks had (there are eighty-eight constellations now), but the constellations of the Zodiac are much older. This makes sense because while many of the constellations can be thought of as “sky-decorations” the Zodiac allowed the ancients to track the seasons. Of the zodiacal constellations, Libra might one of the youngest.

.....Libra as the balance represents that the Sun would be in this sign at the Autumnal Equinox, when the day and night would be equal lengths, or at least it was. According to the boundaries as they are now, the Sun would be in Libra at the equinox from about 2200 BC until about 700 BC. Close to this time, if Libra did not exist as a constellation of its own, then it could have been created, to allow for twelve (one per month) constellations around the zodiac. I imagine (spoken in some Indo-Aryan root), "Okay, we need a new constellation for this point where the day and night are the same length. Remember, everything else on this list is a living thing, hence the 'zoo' in 'zodiac'." Six hours of debate follows, in which Chester (or the Indo-Aryan root for "Chester") rejects a bunch of things because they're "stupid, ten more things are dropped because Bert is allergic to shellfish, the "Claws of the Scorpion" is out because Bob of the High-Pitched Voice sat on one once, and then, "&#@% it, we'll call it the "scales", happy hour is almost over. (The bartender gave the lizard an extra squeeze, or something. Heck, I don't know what ancient beer was like.) Geez, this could have been the first "designed by committee" in history.

.....Even when not using the strict modern boundaries, the wobble of the Earth around its axis (which I discussed in a post on Ursa Minor) would have carried the equinox into Virgo, where it is now (and where it will be until AD 2450). This seems to indicate that Libra as a scales must have existed when the equinox was well inside Libra, but there are many references to these stars as Chelae, the claws of the scorpion. First, as seen below, the stars of Libra work well as the claws of the scorpion, whereas with Libra as a scales, the scorpion’s claws seem a little pathetic. The (seriously cool) names of the stars could refer to this, with Zubeleschamale translating as “the northern claw” and Zubelelgenubi as “the southern claw”. This is contested in some sources (alright, I admit it – in an unsourced article on Wikipedia) in that the Arabic (zubānā) and Akkadian (zibanitu) words for “scorpion” and “scale” are the same. Life becomes more complicated with the constellation having either four claws or four scales, but Richard Allen’s Star Names: Their Lore and Meaning considers Zubelalgubi as a degenerate version of the name “Zubelelgenubi”, and Zubenelhakrabi (the scorpion’s claw) as belonging to g Scorpii, which was apparently due to a need to invent two new claws when the other ones became Libra.

.....Why were the scorpion’s claws made into the balance of Libra (assuming, of course, that this is what happened)? Sure, there would be pressure to have twelve constellations on the Zodiac, one per month, and the reason of having a balance at the point where day and night are balanced make sense, but I have another idea why an inanimate object was added to the Zodiac where it was …

Five minutes before the first sexual harassment lawsuit

.....Zubenelgenubi is a fairly easy double star to split, with the companion star being dimmer, but not tremendously dimmer (magnitudes of 2.8 and 5.2), and about 4 minutes of arc apart, or about one-eighth the size of the Moon in the sky. I could split this double star with a pair of binoculars, so this represents an excellent opportunity to do the same, and take the first step towards learning how to observe and split double stars.

The Summer Solstice

2011-06-21T16:49:00.000-05:00

.....(First, I hope that this is not causing anyone to skip my post on viewing Mercury, posted yesterday.) Here's what set me off. I was directed to a story on the solstice. First I'll give you a post on why this is the summer solstice for the northern hemisphere, and try and keep from going off on the problems I saw in the "news" story. If you are at a cookout, the closer you are to the fire, the warmer you are. If you are getting an English muffin out of the toaster, the closer you are to the toaster, the warmer your hand is. In that case, it seems intuitive that the Earth is warmer when we are closer to the Sun. It seems intuitive, but it is completely, totally, and utterly wrong.

.....The Sun does not move around the Earth (something that is only moderately difficult to get students to accept), but it looks like it does, in the same way that the sky can be treated as a big imaginary sphere. As the Earth rotates, the North Celestial Pole (NCP) is the point in the sky that appears directly above the Earth's north pole, and the South Celestial Pole and Celestial Equator are ... I hope that you get the idea. Since the NCP is directly overhead at the north pole, or 90° above the horizon, and the NCP is on the horizon, or at an angle of 0° above the horizon, we can see that the angular height of the NCP is the same as our latitude. We can then track the apparent path of the Sun across the sky as the ecliptic. Why we have seasons comes from the fact (a fact that does not depend on whether USA Today says that it is true or not) that the Earth does not rotate with its equator in the same plane in which it is orbiting, but is tilted by 23.5°. This means that the ecliptic is tilted by 23.5° to the celestial equator (the Earth's equator projected into space) as shown. The Earth keeps this tilt constant as it orbits, the star Polaris always above the Earth's North Pole, as shown below. (Not to scale.)

.....The effect of this is that during part of the year, the northern hemisphere is "leaning into" the Sun, and during part of the year, the northern hemisphere is "leaning away" from the Sun. Imagine that we pick a point on the Earth, and then trace the path that it takes over one day, a circle inscribed across the Earth at your latitude. The effect that this has on the day comes from two things. First, notice that the point, at the northern hemisphere summer solstice, spend the majority of its time on the sunlit side of the Earth. It is hotter in the summer partly because the Sun is above the horizon for a longer period of time. The northern hemisphere has its longest time of daylight on the summer solstice because the tilt of the Earth points the northern hemisphere most directly towards the Sun on this day.

.....The second reason why summer is hotter has to do with the height of the Sun in the sky. In summer, a quick glance at the diagrams above should show that the Sun is much higher in the sky in the summer, as opposed to the winter. The Sun provides the same amount of energy to the Earth at all times, but if the Sun is low in the sky that same energy is spread over a greater area, having a lesser effect. To take Winona, Minnesota, (with a latitude of 44°) as an example, the North Star is 44° above the northern horizon, which means that the celestial equator is (90°-44°=) 46° above the southern horizon. On the summer solstice, the Sun is above the celestial equator, or a maximum value of 69.5° above the horizon, as opposed to the winter solstice, when the Sun is only 22.5° above the horizon, at best. These two effects combine to make summer hotter, and, as the observant may have noticed, at all times (not just on the summer solstice), the seasons in the northern hemisphere are the exact opposite as seasons in the southern hemisphere.

.....The Earth is actually closest to the Sun in January. This might seem strange, but really, the Earth's orbit is so close to being a perfect circle that this difference is not detectable. One might expect the Southern Hemisphere's summer to be slightly hotter than the Northern Hemisphere's Summer, but the Southern Hemisphere is mostly water, and water has a strong moderating influence on temperature changes.

High Mercury

2011-06-20T23:46:00.000-05:00

.....I'm not referring to the temperatures getting hotter as we approach the Summer Solstice, but the planet Mercury, which is becoming visible in the west after sunset, although I might be overstating that just a bit. Of the visible planets, Jupiter and Saturn are easy to find. Saturn is still bright in the southern sky as it gets dark, and Jupiter is bright in the sky before dawn (slowly moving into the evening sky; by September, Jupiter will be replacing Saturn in the evening). Mars is basically visible every other year, since it is only a bit farther away from the Sun as the Earth, so when the Earth passes Mars, it takes a long time to "lap" it again. Venus, like Mercury, is either a morning star or an evening star, but it is much easier to see (explanation to follow).

.....Mercury (and Venus) orbits the Sun on a smaller orbit than the Earth has. This means that Mercury (for example) can never be high in the sky at midnight because it would then have to be exactly opposite the Sun in the sky. This is clearly impossible. Taking this to a less extreme case, we can see that Mercury will always need to be close to the Sun in the sky. (Mercury also has a very elliptical orbit as well - the most elliptical orbit by far of the official planets.)

.....As you can see from the above view, Mercury is never more than 28° from the Sun in the sky at the best of times, which makes viewing Mercury very difficult. (for the nest few weeks, we are at about the middle between these two extremes.) The Sun is so bright that nothing but the Moon can be seen in the sky with the Sun, so to see a planet, we need the Sun to be below the horizon. That means that Mercury can never¹be seen higher than 28° above the horizon, but it gets worse ...

.....The sky does not suddenly go dark when the Sun goes below the horizon because the light from the Sun is scattered in the atmosphere, so we have to wait longer, for the sky to darken, in order for Mercury to be visible. Astronomical twilight lasts until the Sun is 18° below the horizon, so in the best of times Mercury is only 10° above the horizon, while if Mercury is observed at its closest to the Sun, then Mercury will be setting at dark. Even in this best case, this means that we will be looking at Mercury through a heck of a lot more air. (We don't have to wait for the sky to be completely dark; Mercury is bright enough to show up while there still is some light in the sky, but it can be challenging to see.

.....When looking at an object 10° above the horizon, we are looking through 5.6 times as much air as when something is directly overhead. This would be like setting up your telescope at the bottom of a swimming pool - and it keeps getting worse.

.....The ecliptic is the path of the Sun across the sky. The planets have to stay near (though not on) this line, so at times when this line makes the greatest angle with the horizon (for the Northern hemisphere, this would be March), we have a better chance to see the planet. In June and early July, we are closer to the condition on the right above, than the left.

.....Until the first spacecraft went to Mercury (Mariner 10, in 1972-73), or the second (MESSENGER, in orbit as of this last March), views of Mercury were difficult to get. We had these really bad views, or wait for a solar eclipse (you guys check the footnotes, right?), so the best diagrams looked like those below, a sketch made by the astronomer Giovanni Schiaperelli. This does not look like satellite photos of Mercury (unavailable until 1973, and shown at the right). The sketch below looks more like a captcha than a planet!

Jello?

.....To see Mercury in the next few weeks look close to the horizon just after sunset. For example, tomorrow night, Mercury should appear at about 8:55 when it is about 7° above the horizon. This is less than the angle between your fingers when making the Arachnid Super Hero gesture / secret devil sign (depending on your taste in seventies metal) at arms length. You can see that if you have a wooded or hilly horizon, you are kind of hosed. The best case scenario will be on July second starting at about 9:05 when Mercury will be 10° above the horizon. Woo hoo!

1: Or during a solar eclipse, but that seems like an uncommon an extreme caveat to toss in.

Getting Mooned

2011-06-15T00:21:00.002-05:00

....All photos in this post were taken by the author using a Canon PowerShot A630, sometimes through an 8" Celestron Schmidt-Cassegrain telescope. The camera is held up to the telescope by an Orion SteadyPix Deluxe.

.....If you have been outside in the evenings, you will have noticed that the Moon is getting bigger and brighter each night, heading to a full Moon tomorrow. I have to confess that I've been (perhaps unfairly) biased against the Moon. From the time that I started getting interested in astronomy, I have been searching in the sky for new objects that I haven't seen before, trying to find the faintest thing that I could find. The Moon was therefore my enemy.

.....Furthermore, I could never find the "Man in the Moon". Do you see it below? I don't.

.....I do, however, see the rabbit. The idea of the rabbit in the moon appears in a number of Asian legends, but I think that I'm remembering a story where the rabbit is thrown there. Watership Down? Anyway, if you don't see it, here it is:

.....Zooming in:

.....See? The rabbit even has a carrot. This hatred of the Moon eased when my wife got me an attachment for my telescope allowing the camera to stay still long enough to take images through the telescope. Here is a image of the waxing crescent Moon.

.....Photography actually is helping me enjoy observing the Moon. One of my problems has been that it has been hard for me to adjust to most of the available maps of the Moon. Why this is, I'm not sure. Telescopes will invert the images as we see them. (In most cases, who cares, as there is no "up" in space - except on the Moon.) Antonin Rükl's Atlas of the Moon was much easier to use for me (it seems that there is a revised edition - I wonder what changed), so I was able to map images to place names. This means thta I can learn more about specific places, and then go back later and find them again! Let's start with some of the Maria (singular: Mare), dark areas on the Moon produced from three to three and a half billion years ago when massive impactors hit the Moon hard enough to break through the surface and cause some of the still-molten interior of the Moon to boil up and re-surface the area. Maria typically have few craters, since they were formed after most big things that were going to hit other big things already had. (It is not a thing that could be done twice, after all.) These features are named as if they were bodies of water because they appeared flat and featureless to early telescopic observers.

.....Let's start by looking at some of the Maria best visible during the first half of the month, and as the blog goes on, I will return to the Moon when I can to look at more features, and learn more about the ones we can identify. The photo below has labeled areas including Mare Humboldtianum (Humboldt's Sea, named after an explorer because it lies on the border of the part of the Moon that we can see, and the part of the Moon that we can't see, always on the edge of the unknown), Mare Crisium (The Sea of Crisis), Mare Frigoris (The Sea of Cold), Lacus Somniorum (The Lake of Dreams), Mare Tranquitalis (The Sea of Tranquility), Mare Fecunditatis (the Sea of Fertility), and Mare Serenitatis (the Sea of Serenity)

.....For instance, that footprint, Mare Undorum (the Sea of Waves) and Mare Spumans (the Foaming Sea) - what's up with that?

The Arietid Meteor Shower

2011-06-06T18:03:00.000-05:00

.....Rather unfortunately, tomorrow morning the Arietid meteor shower will be at its peak. Wow! I'm only one sentence in and I already have to explain at least four things ...

.....Meteors, or shooting stars, are small (hopefully!) particles that hit the Earth's atmosphere. Since the Earth is moving through space at about thirty kilometers every second, and the particle is going to be moving bout the same speed, the friction of the air will heat the object to glowing hot as it dissolves. Those flashing lights can come from several sources. Some of them are the flotsam and jetsam of the solar system, little pieces of leftover rock that have been floating around from the beginning of the solar system. Some have actually been blasted off of other planetary bodies, like the Moon, Mars, or asteroids - even asteroids that have been shattered in impacts in the distant past of the solar system. This is compelling stuff, but it is unfortunately not what we are talking about here. Some of these meteors can be seen each night, usually on the order of a half-dozen or so, if you're lucky. (Source)

....Meteors can also be heat tiles, nuts, bolts, tool bags, etc. After fifty years of space travel, a rather astounding amount of space junk has built up in the space around the Earth, to the point where this junk is a positive threat to space travel and new satellites that has to constantly be taken into account. (I had lived for four years in central Florida when I had cause to remember that any object launched into orbit will adopt an orbit that carried it over its original launch point periodically. How disappointing it was to have four years of meteor watching cheapened by realizing that some large fraction of what I had seen was "just" junk!)

.....Meteors can also come from comets. Consider a bright comet, passing through the inner solar system:

.....We see a comet by looking at the bright tail. We see the bright tail because the tail is made of many particles of ice and ice-covered dust released from the comet during eruptions caused by heating from the Sun. These eruptions also release a lot of dust and rocky particles from the comet, and those bits and pieces don't simply disappear when the comet (now the comet et al), moves far enough away from the Sun for the nucleus to quiet down. (We're not allowed to have something simply appear or disappear without a way to explain where it came from or where it went.) The bits that are blasted off stay in the same orbit, although they do spread out through the orbit over time. these ex-comet parts are what give rise to meteor showers.

.....Comets rarely (dramatic understatement) impact the Earth. Even when their orbits cross the Earth's orbit, the chances of the Earth and the comet both being there at the same time are remarkably tiny. However, if the comet has passed by the Sun enough that there is a great deal of debris spread throughout the orbit, the Earth can hit this. Each of these small particles becomes a meteor, and since the meteors are all coming from the same stream, and thus approaching the Earth along the comet's orbit, all these meteors appear to be coming from the same spot in the sky. (The spot where the comet's incoming orbit hits an imaginary shell representing the sky around the Earth.) This spot in the sky is called the radiant of the meteor shower, the point that meteors in this shower appear to radiate away from, and the point for this shower is in the constellation Aries. Hence, this meteor shower is refered to as the Arietid Meteor Shower. (The map is good for 4 AM tomorrow morning.)

.....I said "unfortunately" at the beginning of this post because the above star map, showing the location of the Arietid radiant, shows the sky shortly before dawn. This means that the Arietid shower is a daytime shower, and there are darn few meteors bright enough to be seen during the day. Sure, there is a chance to see meteors in the couple of hours before dawn ...

..... The typical number of meteors per hour for the peak of the Arietid meteor shower is about fifty per hour, but that is misleading. You might (on average) see fifty meteors an hour if your sky was completely without light pollution, and the radiant was directly overhead, but we aren't going to get that. A perhaps sizeable fraction of you paused at my words "before dawn" earlier. Yep, when I suggest that something cool is going to be visible in the sky, nothing kills the joy faster than the words "before dawn". At this point, I might even have negative readers for the rest of this paragraph ...

....So if you aren't willing to get up before dawn (statistically speaking, you aren't) is there any way to detect meteors during the day? As it turns out ...

.....Meteors heat up, glow, and (mostly) dissolve in the upper atmosphere. Along their paths, they leave ionized gases, knocking electrons briefly free, and this can reflect radio waves moving through the atmosphere, causing you to briefly hear radio stations more than a thousand miles away. If tomorrow morning the radio briefly cuts out, or if some station you don't recognize surges for a few seconds, that might be due to the path of a meteor.

.....Or, if you want to try to see some of these, look to the east before dawn. One advantage of these types of meteor showers is that the meteors will move comparatively slowly. This is an advantage if you, like me, tend to be able to summon fast-moving meteors simply by looking down.

The Brightnesses of Stars

2011-05-23T20:24:00.000-05:00

.....One of the biggest problems with just getting into astronomy is learning a new language , made all the more confusing because it looks so much like English. There are a lot of terms which, don't worry, become familiar very quickly, but if you just pulled an astronomy book or magazine off the shelf in a bookstore, can seem to make little sense. I'm going to try to avoid new terms (just for the sake of new terms) where I can, and where I think it's important, I'll call special attention to them, like now.

.....It is hard to start off a column with an apology for two thousand years of common use (so I waited until the second paragraph! woo hoo!), but there is a habit that started with a Greek astronomer about 2300 years ago. This astronomer, Hipparchos, divided the stars in six categories with the brightest stars as "stars of the first rank" and the dimmest stars as "stars of the sixth rank". This seems to make sense until we track this this forward into the nineteenth century, and people are able to take photographs of stars and make absolute measurements of the amount of light coming from a particular star, as opposed to simply "brighter than that other star over there", when astronomers decided to keep the magnitude system.

.....This means that a star with a magnitude of 6.00 is the faintest star that can be seen with the naked eye (I normally use "unaided", but I want this blog to show up under Google searches for 'naked'; heck - naked naked naked) and a star with a magnitude of 1.00 is quite bright. The Sun has an apparent magnitude of -28. This can be hard to track. Still, at this level, we can still use the magnitude system in a reasonable way.

.....Consider this map below, which is the June 2011 sky as it might appear in a magazine such as Astronomy or Sky & Telescope, which shows stars down to fifth magnitude (going all the way to sixth magnitude would add about 1,600 tiny dots to the map; not a great deal of use is added.

.....(I chose to only include stars and asterisms that have come up in the blog. Since this blog is fairly young, that's not a lot.) Even if I had put all the names on the map, consider looking up at a sky like this:

.....If you are just starting out, this can be pretty darned intimidating, plus, unless you live someplace away from cities/car dealerships/McDonald's. I certainly can't walk out my back door and see fifth magnitude stars! We can speak of how many stars we can see by talking about a "limiting magnitude". A reasonably dark, moonless suburb, with no direct lines of sight to street lights, might have a sky with a limiting magnitude of fourth magnitude:

.....As you can see, even with a limiting magnitude of four, "holes" are appearing in the patterns. Move a little bit closer to town (or let the gibbous Moon rise), and we have a limiting magnitude of three:

.....That last one is about what the sky looks like from my back window on a good night. You'll notice lots of holes in constellation patterns; some entire constellations have vanished. At this point, the lack of stars (which might have seemed beneficial to a beginner who did not want to be overwhelmed) now works against us. This is why I started with the Big Dipper and a few bright stars. After all, toss in some thin clouds and we go to second magnitude. (Notice that when we are looking at this map there are a few sets of bright stars. The three bright stars rising in the east we will come back to, in time.)

.....And on a very bad night, if all that we can see are stars of first magnitude or brighter, the sky is fairly empty.

.....Drat. I just noticed that I did not add Saturn to the empty star maps.

Rings Around the May Sky

2011-05-19T22:40:00.000-05:00

.....I love looking at the stars, and I, like a lot of other people, want to help other people recognize what is there to be seen, but if you look at a star map in a magazine like Astronomy or Sky & Telescope, or at a useful web site such as Heavens Above, you will get a skyful of constellations, but you might not have the experience or confidence to use all this. As we go through the sky constellation by constellation, I will add these into the mix.

.....So far, we have only covered the Big Dipper and the bright stars that we can find with the Big Dipper ... plus one. We start with the Big Dipper and stars as it is seen at 10 PM on May first (which is, admittedly, well past). At the beginning of each month, I will post a view of the night sky at 10 PM. Will this be uniformly useful? Often not. In the summer, it might not even be dark at ten, and in the winter it will have been dark for several hours, but this will still be helpful if you observe within a few hours of 10 PM. The map is also set up to show the sky from 44 degrees north, pretty close for most of the northern United States and well set up for Europe, but a viewer in the southern US or Japan would only notice a slight shift in the positions of the stars. SO let's take a look ...

.....Added to this set of stars is the one bright planet visible in the evening sky, Saturn. (Sorry, SATURN!!) If you ave a telescope of even the smallest size gathering dust in a closet, you should definitely get that out, because Saturn is one of the few things in the sky that actually looks like it's supposed to. As I go through the sky, there will be a lot of deep sky objects that can be found in a telescope that (I know from bitter experience) get a response of, "So, is that it? The little fuzzy bit?" Saturn, in a telescope looks like *&^%&^* Saturn. Saturn's rings are clearly visible in even the smallest telescope, and you will definitely know that you have found them. On a good night, the Cassini division, the dark line between the two rings is visible, and Titan - the largest moon of Titan, and the only moon with an atmosphere (but it's still no Yavin IV).

The Northern Lights - maybe tonight!

2011-02-17T18:44:00.000-06:00

.....On Monday, the Sun released a tremendous amount of material and energy in the general direction of Earth, and that material is now encoutering the Earth. The tremendous burst of charged particles, when they interact with the Earth's magnetic field, get forced to follow the field lines until all the particles are spun into a tightening flow as the magnetic field lines get closer as they bend to Earth near the north and south magnetic poles. What happens then is the same as what happens in the flourescent bulbs in your office. The fast-moving charges energize the electrons around the gases they are passing through, leading to a glow in the sky, the northern lights. If you have the opportunity to go outside and look north tonight, take the chance and look towards magnetic north. Maybe you'll see (as I used to, in the Upper Penninsula of Michigan) a greenish semicircle of light around magnetic north ... or maybe something cooler, one of those nights when the whole sky seems like a curtain of fire ...

Moony Monday!

2010-12-19T22:09:00.004-06:00

.....I said "Moony Monday" for the Total Lunar Eclipse that will occur early Tuesday morning because I couldn't think of anything that went with Tuesday. The universe is not rewarding this, however, since there is a winter storm warning with 5-8 inches of snow on the way, finishing up with frozen rain. I hope someone else out there gets a chance to see this.

.....To see this, all you need is a good view of the skies (from the Americas, and best set up for North America). If you have a telescope, or even binoculars, that will make things even better, but it isn't necessary.

The first stage is when the Moon enters the Earth's penumbra, the shadow where part of the Sun, but not all of it, is blocked. This will be pretty much undetectable. The Moon enters the penumbra at: 11:46 PM (CST/ UT -6, which is 12:46 AM Tuesday in the Eastern Time Zone, and 10:46 PM in Mountain Standard Time, and so on.)

.....The Moon enters the umbra, the central shadow at 12:51 AM (again, CST, the best time zone) , and totality, with the Moon entirely in the umbra from 1:57 AM to 3:14 AM. On Earth, a total eclipse is completely dark, but in a lunar eclipse the light passing through the Earth's atmosphere is scattered into the shadow. In the same way that the sky appears blue because blue light is scattered first, and the setting Sun appears red because red light is scattered last, the totally eclipsed Moon will appear a deep red, sometimes getting so faint that the full &^$%&^% Moon is hard to find in the sky.

.....The Moon leaves the umbra at 4:17 CST, so the party is then pretty much over.

.....Since this lunar eclipse happens on the Winter Solstice (when the Sun is at its lowest point in the sky), the Full Moon (exactly on the opposite side of the sky) will be at its absolute maximum possible highest. I'm honestly fairly amazed that no group has come forward claiming some mystic significance for the occasion. There is definite non-mystic significance, because this is the last total lunar eclipse visible from North America until April of 2014.

.....If you do get a chance to see it, please let me know; I'll be watching the snow fall, grading final exams.

An apology

2010-12-19T21:52:00.002-06:00

.....Wow, looking at the time that has gone by, while I very much want to provide a blog that is aimed at those who might not be in the middle of the country with years of experience, I've first gotta go with my teaching responsibilities. Still, I am working toward building up a "Year around the Sky" to start in May. I will still be updating this as often as I can.

Aquila: The Eagle Has Landed

2010-09-19T20:47:00.007-05:00

..... The southern star in the summer triangle is Altair, which means "the Eagle". (Vega, in Lyra, also means "the [Diving] Eagle.") Altair is the brightest star in the constellation Aquila (the Eagle) which is shown in the map below along with the constellations Sagitta and Scutum, which a reasonable reader at this point might conjecture mean "the Eagle" and "the Eagle", respectively, but surprisingly this turns out not to be the case.

.....Altair is the closest of the stars in the Summer Triangle, being about 16.77 light years away. The light that reaches the Earth on the night of September 20th, 2010, left the surface of Altair on December 13, 1993.

.....The constellation Aquila is a fairly large constellation in the center of the summer(/autumn) Milky Way. The view of the Milky Way in the sky even shows a split, with the Milky Way having apparently separated into two bands. This appearance is actually due to tremendous clouds of neutral hydrogen gas and dust between us and the center of our galaxy. We're looking in the direction of a tremendous number of stars, which makes it surprising that Aquila has no deep sky objects of interest in the reach of a small telescope.

.....This lack of cool stuff is why I added the constellations of Scutum and Sagitta to this map; I'm going to describe the telescopic objects in these two constellations in Aquila's place, since Aquila is easy to find, but doesn't have anything of its own.

.....This constellation also stands out to me because I now live in an area in which eagles are reasonably common sights. Just last weekend on our drive along the Mississippi to town, we saw two eagles flying over the road. Upriver in Wabasha is the National Eagle Center, located here because it is the northernmost point along the Mississippi the does not freeze over, so there are many bald eagles that winter in this area. In January and February it is possible to see dozens of eagles along the river, and I don't think that there has been any times in which I have gone there that I have not seen any eagles in wild.

Deep Sky Objects in Lyra (L2/M57, M56)

2010-08-29T21:58:00.000-05:00

.....There are two Messier objects in Lyra, and the up side to Lyra's small size is that I can fit the entire constellation figure on the finder chart for both objects. Lyra contains one of the most impressive, and easiest to find, Messier objects.

Messier 57 / Leckenby 2: The Ring Nebula

.....The Ring Nebula, aka M 57, aka NGC 6720, aka L2 (my designated second object on the "Leckenby list", my list of deep sky objects that a starting observer has a really good chance to locate) is located between the bottom two stars of Lyra, Sulaphat and Sheliak. In a good pair of binoculars, the Ring Nebula can be seen a little bit closer to Sheliak than Sulaphat.
...In a telescope, the Ring appears as a, well, ring. The Ring Nebula is a "planetary nebula" (due to its round appearance), and in the simplest model of a planetary nebula, it represents what will someday happen to the Sun. When nuclear fusion finally stops at the core of the Sun, the core will collapse without that energy being added to it, and that collapse will release energy that will bounce off the outer part of the Sun like an expanding soap bubble. As it turns out, things are a little bit more complex; the Ring isn't actually a spherical bubble of gas, but more of a cylinder that we are looking at edge-on.

.....Below are two images, one of which might be a mistake to include. The one on the left is a sketch I made of the Ring Nebula through my personal telescope. This is probably fairly close to how this object might look to the typical backyard observer. The other image is a Hubble image of the Ring. This object will *never* look like this in your backyard, I'm sorry.

Messier 56

.....Messier 56 isn't viewed as often as, say, the Ring Nebula, because M56 is a globular cluster, and there are dozens of globular clusters visible during the summer. Given a choice between M56, and something like the Hercules Cluster or M5 in Serpens, most people will go for one of the biggies. The most dramatic globular clusters appear as a bright central blur that resolves itself into individual stars as you get farther to the edge. That resolution does not appear with M56, at least it didn't with me. (The seeing the last night I looked at it was not the clearest, however.)

.....the Messier Objects were originally compiled into a list by Charles Messier because he was looking for comets, and these were things that kinda looked like comets, but weren't. Author Stephen James O'Meara has noted that M56 is special to him because it has a hazy, comet-like appearance, so it shows what Messier found distracting when he made a list of what we now recognize as a tour of the wonders of the sky when Messier was just trying to list the garbage that kept getting in his way.

Lyre, Lyre

2010-08-24T17:41:00.001-05:00

.....Lyra the lyre is the first of the constellations of the Summer Triangle; a small constellation consisting of a triangle of stars joined to a parallelogram, but easy to find because it contains one of the brightest stars in the sky. The westernmost star in the Summer Triangle is Vega, and when you can see it over the horizon it the fifth brightest star in the sky. (If someone is reading this over your shoulder, they probably made some joke like, "except for the Sun, dude." I'll wait for a second if you choose to slap them.)

(All good? Yeah, I feel better, too.)

.....Vega is actually one of the stars we use to define the "magnitude" scale that defines the brightness of stars. Originally, this system goes back to the Greek astronomer Hipparchus, who defined the brightest stars as "stars of the first rank" and the dimmest stars as "stars of the sixth rank". Now that we can use cameras to measure exactly how much light we receive from a star, it is now possible to be a little bit more precise. Vega and Arcturus (in Boötes) were use to define zero magnitude. In this reconstructed system, stars with a magnitude of 1.00 are bright, stars with a magnitude of 6.00 are just barely visible one a clear, dry, dark night, and the Sun has a visual magnitude of -27.
.....The only stars brighter than Vega are Arcturus (just barely), Sirius (a winter star), and Canopus and Rigil Kentaurus (stars not visible from the middle and upper United States).

.....The second brightest star in Lyra, Sheliak, is special in another way. Like most stars, it does not travel through space on its own, but Sheliak is actually two stars orbiting closely to each other. As I said, most stars travel in pairs (or more), but these two stars are orbiting so closely to each other that the shape of both stars is distorted, and material is apparently escaping out of the "back end" of Sheliak A. Incredibly funky physics, but you can't see anything through a telescope.

.....What you *can* see in a telescope is Epsilon Lyrae, the other star in the triangle at the top of Lyra. This might look a little funny in the star map, and this star in even a good pair of binoculars will be revealed as a pair of stars. If you then look at Epsilon Lyrae in a telescope under high power, each of these stars is revealed as another pair of stars; Epsilon Lyrae is known as the "double-double" star, four stars (two pair) appearing as one.

.....Numerous times in the past, I have shaken loose from the constellations of the past merely held on to because, ooh, the ancient Greeks created all of western civilization, big whoop, so as I proposed in my last post, I'm replacing the lyre with the lyrebird. After all, how many of us own harps in this day an age? I myself only have one CD of harp music. Hey, it was at a concert; support artists, art establishes and maintains the common culture! You like culture, right? (If you are next to someone who answered no, remember, engineers are often helpful to society as well.)

NEXT: Telescopic objects in Lyra

The Birds of Summer

2010-08-19T09:46:00.007-05:00

.....One of the problems that can keep people from moving from a peaceful contemplation of a dazzling array of stars to finding the dazzling variety of clusters, nebulae, and galaxies that are surprisingly accessible once you make the shift from seeing the sky as a featureless expanse of stars to recognize patterns that will allow you to find wonders hiding in plain -er- slightly assisted sight.

.....Starting in the summer (but lasting until November), three of the brightest stars in the northern sky form a (duh) triangle that covers much of the sky. This "triangle" that first appears in the "summer" sky is called the Summer Triangle because at some point, astronomers got tired of doing things like grabbing a rough pentagon of fourth magnitude stars and calling it "the giraffe"

.....The three bright stars are in three different constellations because the Summer Triangle really does cover a large selection of the sky, and ancient astronomers invented constellations to be able to break the sky into manageable pieces, so they weren't going to invent constellations that tokk up most of the sky. Well, not more than once, anyways. The three bright stars are Altair, Vega, and Deneb, in the constellations of Aquila, Lyra, and Cygnus (the next three constellations I'll write about), and you can use these to do a bit of traveling into the past. Altair, the southernmost star in the triangle, is about 16.8 light years away. This means that it has taken the light from Altair more than sixteen years of traveling through space. The light that reaches us on Friday left Altair about November 12th, 1993.

.....In the northwest, the brilliant star Vega appears to be a step brighter than Altair, but it is actually giving off more than four and a half times as much light into space than Altair does, but Altair is closer. Vega is 25.3 light years away, which mean that Friday's light from Vega left about May 2nd, 1985.

.....The third star, Deneb, is the faintest of the three as seen from Earth, but it actually gives off more than 60,000 times as much light as the Sun does. If we wanted to move Earth to Deneb and get as much light as we do now, we would have to move the Earth to be seventeen times as far away from Deneb as Pluto is from the Sun. Deneb is more than three thousand light years from our solar system, meaning that the light we see now has been traveling through space since 1218 BC, when Ramses II (the Great) was Pharoah of Egypt, and the Trojan War was going on*.

.....These three constellations will be the next three that I write about, Cygnus the swan, Aquila the Eagle, and Lyra the Lyre ... y'know, since two of these three are birds, and since I have felt no compunction about changing constellations, let go ahead and change Lyra to the Australian Lyre-bird, and have these three as as the birds of the Summer Triangle. There are a couple of small constellations that will also show up: Sagitta the arrow, located inside the Summer Triangle, and Scutum, the shield, which I will discuss along with Aquila the eagle, because Aquila has no Messier objects of its own.

* or at least this falls into the range of time in which the original Trojan War took place.

The Moon in the Sky

2010-08-12T16:07:00.010-05:00

.....In response to a couple of questions, I've tried to come up with a device that would help one work out when the Moon will rise and set, and what part of the sky it will be in for any given time of day. This is my result. First, start with the base of this ("Lunalabe"? ""? I need a better name for it), a wheel that another, smaller wheel will move in.

.....Once that is done, find a way to attach this smaller wheel so that the two wheels have a

common center. The way that I first did this was to use a paper clip; an alternative would be to go to a craft/scrapbooking store and buy a specialty brad which can attach through the center. Perhaps it would be better to use an eyelet, or something that has less of a chance of ripping - we're really at the end of my know-how on this subject, but you can check out my crude attempt in the photograph below.

.....Here is how this works, if you know the phase of the Moon, or when the new and/or full moon is that month (you can find these on many calendars, plus, I will now begin posting that information at the beginning of each month. For August, 2010:

Last Quarter: August 2

New Moon: August 9
First Quarter: August 16

Full Moon: August 24

The lunar month is 29.5 days long. This means that the time between phases is roughly one week, which we can use to find the Moon between these dates. Consider this Friday, August 20th. This is midway between First Quarter and the Full Moon, so we start by looking on the wheel between the First Quarter and the Full Moon. The Moon between the New Moon and the Full Moon is waxing (increasing), and the Moon between First Quarter and Last Quarter is gibbous, so the phase of the Moon on Friday will be "waxing gibbous". This has a "+9" by it, which means that the Moon (all else being equal) will rise, set, everything, nine hours after the Sun does. If we take as an average that the Sun rises at 6 AM, gets as high in the sky as it is going to get (transits) at noon, and sets at 6 PM, this indicates that on Friday, we should expect the Moon to rise at 3 PM, transit at 9 PM, and set at 3 AM.

.....This is where we also have to look at the outer wheel. Line up the lines representing the direction of the Sun (the wheel works because as far as the Earth and the Moon are concerned, the Sun is so far away that it is not a point to examine in perspective, but a direction) is coming from "August". (This also shows that in late August the Sun is in front of the stars of the constellation of Leo.) Imagining a line from the center of the wheel out to the constellation ring, the Moon on August 20th should be in front of the stars of Sagittarius. Sagittarius has a "-2" next to it, because Sagittarius is far to the south, and so this constellation is not above the horizon as long as the others. (The Sun is in Sagittarius in December and January, and the Sun is not above the horizon as long as it is in later months.) The "-2" means that in this constellation there will be two hours less time above the horizon at rising and setting, so we expect to Moon on Friday to rise at 5 PM, transit at 9 PM (this does not change), and set at 1 AM. If we compare this to the actual times, the Moon will rise at 6:01 PM, transit at 10:30, and set at 3:03. This seems wrong, if you don't take that hated Daylight Savings Time into account.

.....Tell you what, during DST, just shift your predition forward one hour, so our expected times are Moon rise at 6 PM (pretty close), transit at 10 PM (close-ish, I make no promises to be exact), and Moon set at 2 AM (admittedly sketchy - I might need more work on the hour modifiers on the outer wheel). Still though, this first version does provide a decent rough time, and it identifies where the Moon will be in the sky well. You can use this to help learn the constellations along the path of the Sun and Moonin the sky (the zodiac), as long as the Moon is not too bright.

.....On the other hand, if you see the Moon in the sky and you recognize its phase,this can be used to find rise/set times from that as well. This (I certainly hope) will help you find the Moon in the sky, and this will tell you what constellation it is in.

.....Please let me know if there is a feature that you would like the wheel to do that you do not think that it does, or if there is a feature that is too distracting. If you would like to try this, I have the images as two pages in a PowerPoint presentation at this site.

.....SPECIAL NOTE FOR TEACHERS. I use this device in class to try to illustrate the relationship between the Earth, Moon and Sun defines the appearance of the Moon. If you would be interested in something like this, please let me know, and we can compare notes.

The Perseid Meteor Shower, 2010

2010-08-03T16:28:00.006-05:00

.....Every dark, moonless night not dominated by city lights, we can expect to see a few shooting stars per hour, flashing randomly across the sky. These typically come from one of three sources: Leftover bits of flotsam and jetsam that have been floating around the solar system for the last five and a half billion years (cool), little bits that have been boiled off of comets as they passed around the Sun (also cool), or nuts/bolts/heat shields/tool boxes that have come off of space craft and are crashing back down to Earth (less cool).

.....Each time a comet passes through the inner solar system, if it still has much of its original ice, that ice will boil off, taking some dust pebbles with it, and the ice will reflect sunlight, resulting in the bright coma and tail. What happens to this once the comet goes back to the outer reaches of the solar system? Nothing. That comet rubble stays in orbit, resulting in the comet's orbit eventually becoming a dusty tube of gunk around the Sun. If the Earth should pass through this gunk, then when the particles hit the Earth's atmosphere they will light up from the heat of friction generated from going from a temperature of less than three hundred degrees below zero (Fahrenheit) to thousands of degrees. Since all of these meteors are coming from the same general area in space, they will appear to come from the same general area of the sky, meaning that the meteors will all seem to radiate out from the same point. (Called, reasonably enough, the "radiant".)

.....Each August, the Earth passes through the remnant trail of the comet Swift-Tuttle, generating the Perseid meteor shower because the radiant of the meteors (the dotted circle in the image below) is in the constellation of Perseus.

.....The Perseid meteor shower does not require a telescope or binoculars; just go outside (especially on the nights of Wednesday, August 11th and Thursday, August 12th, and look to the northeast (especially after midnight).

.....Of the the backyard astronomy I have done, I have a special regard for the Perseid Meteor Shower. Because it does not require special equipment, special practice or special skills, it is easy to share with others. (Also, since observing the Persieds is just looking at the sky, there is no "one person at a time effect that you get with a telescope.) Last year, one of my friends told me about taking his son outside to see the meteors. I've gotten other mail about people who have had their parents show them the meteor shower, and have then shared it with their children. For me, the Perseids were one event I could most easily drag people out to see, often going to visit family with dark skies, or just setting up lawn chairs behind the house, or (one time) my parents even took us to a state park to watch the meteors. For me this gives the Perseids a fairly personal level, especially since my father passed away two and a half years ago. When I would have my telescope at home, it would always be easiest to interest my Dad in coming out and looking at the sky, so there were a lot of times he (and others) would come out, but the Perseids could get everyone out, so its something of a family holiday in my book. I hope that you have the opportunity (weather) to give it a try this year. There will be no bright moonlight those nights, so the sky should be quite dark.

.....Here is a map of the northeastern part of the sky on Thursday at about midnight. Please let me know if you have traditions about the Perseids, or if you have a chance to observe them! If you are in the Winona, Minnesota area, there will be a public observing session at Saint Mary's University of Minnesota. Turn in at the lower gate (across from Goodview Road) and drive straight (i.e., don't make any turns) to St. Yon's Hall. We will set up on the field next to St. Yon's. Bring your own chair/blanket/keep-my-rear-end-dry-device!

Objects in Hercules: The Leckenby List Begins

2010-07-28T15:01:00.015-05:00

.....The constellation of Hercules is pretty large, sprawling through a fairly dim part of the sky, and it contains of number of excellent deep-sky views. Four of these make good targets even in the light-polluted skies that most of America now has. Two of these appear on Charles Messier's list of Messier Objects, one is a fairly obscure open cluster, and one is a planetary nebula.

.....Let me take a moment to look on the catalogs that we are using. The two globular clusters (the first among many, many of these types of clusters visible during the summer) are best known by their Messier designations, although there a lot of catalogs in astronomy because, hey, there's a lot of stuff. If some new object is identified, generally it is listed in the next catalog instead of bringing the old one up to date (the Messier Catalog itself is an exception to this). The Great Cluster in Hercules is known as M13, NGC 6205, GCI 45, 2MASX J16414163+3627407 (what it gains in precision it loses in convenience), and now (at least as far as this blog is concerned), L1.

.....There are, clearly, many different catalogs. Why add one more? What possible use could this "Leckenby List" be? When I first started observing, in seventh grade, with a "telescope" on a tripod that I had to balance on the bar of our chain link fence, I tried to use the Messier Catalog as a guide for objects to find. After all, most of the bright objects in the sky are in the catalog, but not all of them are. I wanted to set up a list that had all the cool things that one could find with a small, suburban telescope, and the Messier Catalog left stuff off that list. There is another Catalog that is of recent vintage, the Caldwell-Moore Catalog, set up to include cool things that Messier left out, but like the Messier Catalog, that also includes objects that are too faint, or too diffuse to be seen in light-polluted skies. The Leckenby List will try to include interesting things that can be seen by a fairly new observer on a perhaps somewhat sketchy night. That's my goal.

.....Globular clusters are actually outside of the disk of our galaxy (while they do orbit the center of the Milky Way), and they consist of some of the oldest stars we can see, forming before the stars in the disk of the Milky Way began to collect.

M 13 or L1

..... The Great Hersules Cluster is one of the two best globular clusters as seen from the continental United States. (If anyone is reading this from southern Florida or Texas, please don't bring uop the much larger and brighter globular cluster Omega Centauri. Thanks.) Tghe Great Hercules Cluster has more than three hundred thousand stars, and it so large that light takes more than 130 years to pass from one edge of the cluster to the opposite edge. It is only that the cluster is at a distance of 23,400 light years that keeps it from appearing even more impressive. M13 is fairly easy to find. Looking at the keystone of Hercules, start with zeta Herculis, one of the stars at Hercules' waist, and scan north. When you are most of the way to eta Herculis, the Hercules Cluster will appear as a fuzzy spot between two stars that sppear brighter than their neighbors. M13/L1 is visible even in bionoculars, which is one reason why I have included it as the first object on the Leckenby List.

As seen in a small telescope, M13/L1 appears as a tight ball of stars, with the stars near the edge (where the density of stars starts to thin out) clearly resolvable as indivindual stars, while the stars near the center blur together). To my view, there are a couple of "arms" of stars that appear a little denser than the other areas (although to be fair, photographs show the stars as pretty uniformly distributed). I would be very interested if there were anyone else out there who had an opinion on whether their own observations showed anything like this.

M92

M92 is the other Messier Object in Hercules, and it is also a globular cluster. This can be found fairly easily by starting at the northeast corner of the keystone. If you are looking at this star in binoculars or in a telescope's finderscope, you will see two stars next to pi Herculis, and a set of bright (in binoculars) stars forming an asterism that I christen "the l'il kid" reaching up above his/her head (the existing stars in the star pattern prevent a greater level of detail in the gender of the figure) for the asterism that I name the "Trademarked Fying Disk Toy" (I don't want to get sued), and abovve that, M92 as a ball, these two objects apparently stuck on an invisible roof that the l'il kid just can't reach.

.....Sadly, I haven't observed M92 nearly as much as M13/L1, so I have less of an idea of it's individual observing character. M92 is about two-thirds the apparent size of M13/L1, while only being a little (comparatively) farther away

DoDz 9

.....The next object to look at is a small cluster labeled as Dolidze-Dzimselejsvili 9 is a group of about fifteen stars. Honestly, I do not know if this is an actual cluster of stars that all formed together, or if this is just how it appears. Even the name does not help that much because the DoDz list only has nine objects on it, and the list itself is pretty obscure. Start with the end of Hercules' western arm, and even binolculars should show you this cluster (I think).

.....This is my diagram of this cluster, and I couldn't find a photo or setailed chart to let me know if I was even looking at the right stars. Does someone else have a take on this?

NGC 6210

.....The fourth object is NGC 6210, deriving its lovely, poetic, name from the New General Catalogfrom the 1840's, so called because it replaced the "General Catalog of the 1820's. So there. Nebulae of all types are often hard to see from suburbia as light that is smeared across the sky can be more easily drowned out by the local Wal-Mart (sadly, there's always a local Wal-Mart) that light concentrated into points (stars). Planetary nebula are even more rare because they are the bubbles of ejected gas given off by stars around the same mass as the Sun as those stars finally go the Great Retirement Home in the sky (which is, at least, actually in the sky). These bubbles are often round, as soap bubbles are, and this round(ish) appearance gave them the name "planetary nebulae".

.....I have a finder map for this object that do not have the constellation lines on it because those lines can interfere with finding the object. If you can start from beta Herculis, you should be able to star hop to the nebula, although I don't have .

If you can get to where NGC 6210 shoul be, it should be observable as a small but distinct blue ring, the light concentrated enough to be bright enough to see and just large enough to be identified as a planetary nebula.

July Sky

2010-07-15T20:48:00.003-05:00

.....While I work on the observing maps for some deep sky objects, I don't want to miss the forest for the trees, and so here is a sky map for July. (Constellations that have been discussed on this blog are in blue, and constellations I have not gotten too yet are in red.)

.....The Big Dipper is still in the sky, as it will always be in the sky from the northern US, but some constellations that you can find from the Big Dipper (Boötes and Virgo) are moving off to the west. In the east we can find the Summer Triangle, built using three of the brightest stars in the sky. This set of stars (despite its name) will be in the sky until early winter.

.....This map only includes stars brighter than fourth magnitude, so some stars in the constellations are "missing". If you are just learning the constellations, or if you are viewing from a light-polluted sky, I hope that this will be a better way to find the brighter stars.

.....Start making plans now for the Perseid Meteor Shower! Peaking on the nights of August 11th and 12th, this meteor shower can result in dozens of meteors an hour! This year, the Moon will be out of the sky on these nights, so the sky will be at its darkest. This will hopefully be a great year for the shower!

My Delays

2010-06-29T13:26:00.002-05:00

.....I haven't gotten a second post up this month, something which was certainly not my plan. Here's my excuse: We went to my granmother-in-law's birthday party, came back, were visited by a good sized chunk of my half of the family for a week, and then went back and visited the in-laws in a more leisurely fashion. Soon (I promise) I will have up a post on things that a small telescope, operating under streetlights, can find and see in Hercules, then a post on the phases of the Moon, then a post on why working for a dark sky is also healthier, more environmentally friendly, and *safer* than sticking street lights every five feet. Then more constellations.

-- Harry

Hercules, or "There?", "No, next to it", "There?", "Kinda"

2010-06-02T10:32:00.006-05:00

..........Hercules is a constellation of fairly dim stars surrounded by brighter constellations. One might consider just skipping over these stars, but there are some beautiful binocular and telescope objects located in this constellation (the subject of my next post), and these objects make the hunt worth the wait. These objects will also trigger the start of what I am modestly) calling the "Leckenby list". There are many different lists of deep sky objects, the most well known of those being the Messier Catalog, but much of my observing history has been from suburbia, where a lot of even the Messier objects are invisible in a small telescope, and where there are a number of other cool deep sky objects that Messier, for one reason or another, did not see fit to put on his list. There are other lists, such as the Caldwell list, that look at deep sky objects that are in the same range as the Messier list, just not recorded by him, and some bright, wide objects that these lists have considered as too obvious or outside their scope (rim shot), such as double stars. The Leckenby List is my list of cool sky objects that can be seen with a small telescope in suburbia. You don't have to go through what I did, hours of effort to find some object that I've been promised is there, only to discover that I am looking at it, I just can't see it.

.....It is the purpose of a later run through the sky to go into more depth on the story and legends behind the constellations. In any event, I will go under the assumption that if something makes Disney, the basics are fairly well understood.

.....(Although this movie left out Hercules killing his wife and children in a drunken rage. They must be saving that for the sequel.)

.....As far as that goes, if you're going to look for one of the popularizations of Hercules, I'd seek out the Steve Reeves movie versions from the late 1950's. These were brought to my attention by the Mystery Science Theater 3000 versions of Hercules and Hercules unchained, but if your standards are a little relaxed (three beers, or it is 4 AM in the morning, or some such) these movies are as good as any from the era and from the genre. Better than, say, Clash of the Titans (either version).

.....The constellation of Hercules can be found between the constellations of Corona Borealis (or, "The Kite-Eating Tree", if I can get that to catch on) which is relatively easy to find, and the constellation Lyra, easy to find due to the presence of the bright star Vega. (Vega and Arcturus are two of the brightest stars in the sky, and Hercules is roughly between them.) Find the constellation by looking for the two rhomboids that make up the central body of Hercules. The northern one, smaller and a little easier to find, is called the "Keystone", and this will be our starting point for two bright globular clusters in this area.

.....Looking at this, you may find the presence of Hercules less than obvious. That is, looking at this once you finally find it in the sky. (No slight is intended. I've been observing the sky since I was seven, and Hercules is on of those constellations that I have to find, as opposed to just jumping out at me. In fact, on the Mystery Science Theater 3000 episode in which Joel and the 'bots watch the first Hercules movie, they comment on how most of the constellations don't seem to make sense, and Tom Servo attempts to reframe the constellations in terms of modern sensibilities. (You can watch it at this link; the relevant segment starts at about 3:09.) In honor of Tom's work, I'm going to rechristen this constellation into our modern form (joining the Kite and the Kite-Eating Tree) as something that these stars resemble as much as they do any version of Hercules, I give you ...

.

..

...

....

.....

Pablo Picasso's Cubist masterpiece, "Guernica"

Libra: the Balance or the Scorpion Blocker

2010-05-28T08:50:00.004-05:00

.....Libra is the first of the constellations along the Zodiac that I have written about here. (A curious reader might look at the current star map and wonder why I didn’t start with Virgo, much higher in the sky right now; the reason is that I am not just working my way around the sky, but that on this first pass I’m centering on the brightest of deep-sky objects, things that can be seen with a small telescope. Of the various types of deep-sky objects, the hardest to view are galaxies, and Virgo is so chock full of them that I am saving this constellation for last.)

.....What is the Zodiac? Well, the ecliptic is the path that the Sun takes through the sky, and the planets all stay within 7° of this line (If we skip Mercury, all the planets are within half this distance of the ecliptic). The ecliptic passes through twelve constellations (traditionally; as the constellations were given boundaries by the International Astronomical Union in 1930 the ecliptic passes through thirteen constellations), and these constellations are the Zodiac. Besides being the only zodiacal constellation with no Messier objects, Libra is also the only zodiacal constellation named after an inanimate object.

.....Our constellations can be traced back to the forty-eight the Greeks had (there are eighty-eight constellations now), but the constellations of the Zodiac are much older. This makes sense because while many of the constellations can be thought of as “sky-decorations” the Zodiac allowed the ancients to track the seasons. Of the zodiacal constellations, Libra might one of the youngest.

Five minutes before the first sexual harassment lawsuit

.....Unfortunately, Libra is pretty boring as far as deep-sky objects are concerned. There are no open clusters or nebulae in Libra, and the galaxies and one globular cluster in Libra fall far from being easy to find. I’ll address these on my next pass. Zubenelgenubi is a fairly easy double star to split, with the companion star being dimmer, but not tremendously dimmer (magnitudes of 2.8 and 5.2), and about 4 minutes of arc apart, or about one-eighth the size of the Moon in the sky. I could split this double star with a pair of binoculars, so this represents an excellent opportunity to do the same, and take the first step towards learning how to observe and split double stars.

Ursa Minor, or Shakespeare Screws Up

2010-05-21T15:02:00.005-05:00

Caesar: …” I am as constant as the northern star,
Of whose true-fix’d and resting quality
There is no fellow in the firmament.
The skies are painted with unnumber’d sparks,
They are all fire and every one doth shine,
But there’s but one in all doth hold his place”

Julius Caesar, Act III, scene I, lines 60-65

…..Shakespeare was a hack. More on this later.

…..A blog on Ursa Minor, the Little Dipper, is going to demand that I go pretty far afield to try and make this interesting because this is a pretty inconsequential constellation. The Little Dipper is probably the most famous constellation that almost no one can find. The constellation is always above the horizon literally until you reach South America as you go south, but except for the three brightest stars, including the Pole Star, Polaris, the rest of the constellation is so faint that it can be lost under pretty much any background light.

…..Ursa Minor, quite frankly, has its name write a check most of its stars can’t cash. The constellation would be quite ignorable if it were not for the star Polaris, and from Greek times to the Renaissance this constellation was sometimes referred to as “Cynosura” (what a translation to this word means is not known, but it probably has something to do with a dog) and sometimes that name only referred to the brightest star in the constellation, so for most of human history the general reaction to the constellation is, “The heck with it, just deal the bright, useful star.” (A reasonable question might also be “Why not just call it, like, “Polaris” or something that shows that since it’s by the Pole, and this brings us to one of Shakespeare’s mistakes. Again, more on this a little later.)

.....Polaris has its name because it is very, very close to the North Celestial Pole. To see why this is doubly lucky, let’s look for a moment at how the sky appears. Obvious statement of the day: the stars are all very, very far away. So far away that even as they move through space, a time traveler stepping from a clear night in first dynasty Egypt to tonight would only notice a shift in a handful of the stars with respect to each other, and even then only if that time traveler had some pretty good measuring tools. Because of this, it is useful to treat the sky as a dome, or as a globe that we see the inside of from the Earth. To map this, we use the Earth to help us. Consider the Earth as spinning inside this gigantic sphere; one thing that we could "see", projected against the heavens would be the sky appearing to turn as we spun beneath it. Projected on the sky, we could trace north and south poles above the Earth's north and south poles (called the North and South Celestial Poles, reasonably enough), and the Celestial Equator above the Earth's equator. The North Celestial Pole is less than half a degree of arc away from Polaris, so if you were to sit and watch the sky over the course of a night (an eminently worthy endeavor), the stars would appear to whirl around the sky, with only Polaris remaining still. (The South Celestial Pole has no stars of note anywhere near it.)

.....Even Polaris has gotten a reputation beyond its actual means. Because of the usefulness of Polaris, (perhaps) the true idea that Polaris will help you find where you are has led to the (false) idea that Polaris is inordinately easy to find. As I discussed in my post on the Big Dipper, and repeated in my map on the previous post, Polaris can be identified by using the two stars at the end of the bowl of the Big Dipper (which is relatively bright), but a surprisingly common misconception is that Polaris is the brightest star in the sky. How this came about, I certainly don't know. (Polaris is actually the 47th brightest star in the sky.) This has led one friend of mine to increase the "Don't Get No Respect" quotient for this constellation by arbitrarily and willfully defining the brightest visible star as "the North Star". (Hi, Trish!)

…..Besides the three brightest stars, the others are fourth, fourth, fourth, and fifth magnitude, this definition of brightness stretching back to the ancient Greeks when the astronomer Hipparchus divided the stars by their brightness, ranking the stars from “first rank” (the brightest) to “sixth rank” (the dimmest). The other stars that observers expect to see from the constellation figure are dim enough so that a hazy evening, a bright Moon, or the ubiquitous nearby Wal-Mart (in case you didn’t think that Wal-Mart was evil enough) will make these stars impossible to see. In seventh grade, when I got my first chance to study astronomy institutionally, one of our assignments was to sketch constellations we found in the sky. I saw a lot of students turn in the Little Dipper, but none of them got the right stars, a trend that I notice up to today. (A second thing is that I notice Wal-Mart is apparently in Microsoft’s spell-checker; Scorpius: No, Capricornus: No, Wal-Mart: yes – be afraid, be very afraid …)

.....Going back to that hypothetical time traveler, however, the sky as a whole would have shifted noticeably, because the Earth does not sedately simply rotate on its axis, that axis is tracing out a circle on the sky like a tremendous top, with a period of 26,000 years. This wobble is now pointing at Polaris, getting even closer as this century goes on, but in Julius Caesar's time, Polaris was more than ten degrees away from the pole (the "Secret Devil Sign", in memory of the recent death of Ronnie James Dio), making a definite loop during the night. Our time traveler would have seen Thuban (also on the map) as the North Star, and if you wait for about 13,000 years you will see Vega, in Lyra, as the pole star, and that truly is one of the brightest stars in the sky. This is Shakespeare's astronomy mistake in Julius Caesar.

….As far as anachronisms in Shakespeare go, though, this one is not the biggest, even in that play. In Act II, scene i, line 191, Brutus says “Peace! Count the clock.”, and in Act II, scene ii, lines 114-115, Caesar asks “What is’t o’clock?”, to which Brutus responds, “Caesar, ‘tis stricken eight.” Mechanical clocks in the time of Caesar (actually invented in the thirteenth century AD) would actually be less of an anachronism than, say, giving Macbeth Iron Man’s armor…

“Is this a transistor I see before me, the bipolar junction toward my hand?”

.....Oh sure, you might say that Shakespeare didn't know any better but he was able to come up with more appropriate way to discuss time earlier in the scene I just quoted, when Brutus says "I cannot, by the progress of the stars,/ Give guess how near to day." - lines 2-3.

…..Ursa Minor is an important place being filled by a rather boring occupant that is still bright enough to fulfill a useful purpose. (Like Al Gore - Zing!) Yes, I know that this would have been funnier ten years ago. Let me try this again ...

…..To sum up, Ursa Minor is a dim, dark, empty place with only a couple of bright points – kind of like Lower Michigan (Double Zing!)

The May Sky

2010-05-19T10:05:00.005-05:00

.....There are many books and websites to help people who are good at astronomy become really good at astronomy, and many books and websites to (apparently) help people who live in the country where the sky gets what could actually considered to be dark (or at least where you don't have a direct line-of-sight to eight outdoor lights), but a lot of this can be counterproductive if you are just trying to start out, or if you just live where the sky is bright enough to hide a lot of the stars from you. Hopefully, this blog can be useful in both of these cases, but I realized that I might lose some of the benefits of talking about constellations if you aren't able to easily find those things in the first place, so I made a series of maps.

.....All of these maps show the sky as it is seen from the latitudes of the northern US about eleven PM (tonight), or about when the sky finally gets dark. The first map just shows the brightest stars, so while the constellation figures are missing stars, hopefully this stripped-down maps will help you find those constellations to begin with. (As you might see in just a moment here, sometimes star maps that have all visible stars can seem a lttle "busy", and be hard to follow. Also, in all maps the constellations in blue are the ones that have already been discussed in some depth in a blog post, and the constellations in red are the ones that I have yet to get to. Looks like a busy summer.)

.....Heck, even just giving these constellations might not be that helpful. After all, what I have is a representation of the sky as the inside of a giant bowl, flattened out and seen from the inside. In the spring and early summer, the Big Dipper can be used to find the North Star at the tail of Ursa Minor (the Little Dipper), Regulus, the brightest star in Leo, and following the arc of the stars of the handle leads to Acrturus, in Boötes, and then on to Spica, in Virgo.

.....With that (hopefully) as a means to help you find the constellations of the brighter stars, here is a map of the whole sky, helping you if you do live somewhere where the whole sky can be seen, and perhaps frusting you a little bit if you don't.

.....Note that the planets Mars and Saturn are both visible in our evenings! Both planets are about as bright as the star Spica, the brightest star in Virgo (and the end of the great arc from the Big Dipper's handle) Mars does not show much (to me, at least) beyond a disk in a telescope, but Saturn looks so phenomenal as to almost seem fake in even the smallest telescope. If you have anything, even an old department store cardboard 'scope, give Saturn a try!

.....As always, individual maps can be downloaded from this site.

Boötes-licious

2010-05-13T13:53:00.007-05:00

.....Astronomy, by definition, is a study that encompasses the universe, and so there is are many different new things that a study of astronomy can bring you across. For example, I learned that the symbol on the second “o” in “Boötes” is not an umlaut, but a dieresis, indicating that both letters are to be pronounced. I have been presuming that this makes the pronunciation “Bu-u-tez”. I could well be wrong, but since the constellation is never going to get offended, who cares?

.....In legend, Boötes is a herdsman with his dogs (the constellation Canes Venatici) chasing the Great B ear (Ursa Major) forever around the pole, from the latitudes of the northern United States only getting six hours below the horizon a day to rest from the chase. A quick look at the star map will show that this legend is proof that the ancient Greeks had no knowledge of kites. If we were to remake the constellations today (a scheme which has been tried before, remind me to tell you about that sometime), Boötes would almost certainly be “the kite”.

.....The second constellation that I’m looking at in this post is the Northern Crown, Corona Borealis. If I may digress for just a moment, when I was much younger, carrying my telescope out to an extraneous plot of land behind our house, one of our neighbors asked me about what constellations were visible, and when I got to this one, he said,” No. That’s not it. I’ve seen that before and that’s not it!!!” (He didn’t shout, but he was speaking very definitively and I’ve learned that nothing is more definitive on the internet than using three exclamation points.) I realized pretty quickly that he was thinking about the northern lights, the *aurora* borealis, but I cannot remember if I tried to explain that, or just thought, “Whatever, old dude” (or whatever the early 80’s version of that was) and went on.

.....At least Corona Borealis looks kind of like a circlet of stars, but recreating Boötes would allow us to reimage the second constellation that we are looking at today, Corona Borealis away from being the Northern Crown into, say, the Kite-Eating Tree from Peanuts.

.....(I know that the kite appears larger than the tree; it’s foreshortening. The tree is in the background, waiting for the kite to slip up, drift away and get caught. If this story seems too grim for backyard astronomy, please reread the original myth.)

.....As far as telescopic objects in these constellations go, there are pretty slim pickings for the suburban astronomer. The North Galactic Pole is on this map, which means that these constellations are as far away from the pale band of the Milky Way in the sky as it is possible to get. There are a few galaxies in these two constellations, but all of them are close to the limit of visibility for a backyard telescope on the best of nights. I shall try and find each one, and then come back with an update, but I really would not be expecting very much.

.....While Boötes and Corona Borealis don't have any bright deep-sky objects, they do have a couple of bright double stars that small telescopes can reach. Most stars aren't like our Sun, traveling alone through space (yes, I like the planets, but they are very tiny things compared to a star), but travel in packs of two, three, or even more. The vast majority of these stars are so far away that we can't even see them as individual stars, but some of the closer ones can be "split", as it were, in a small telescope. The two things that I look for when looking for interesting double stars are that the stars are of close to the same brightness (so one does not overwhelm the other) and are far enough apart againts the sky to be split. It also helps if the pair is bright enough to be found easily in the sky. The brightest and best in these constellations is Izar (epsilon Boötis). The two stars have magnitudes of 2.5 (bright enough to see from suburbia) and 4.9 (bright enough to be seen from some nice, quiet farmland), but they are quite close together, with a separation of 2.8 seconds of arc, or about 1/600th the size of the full Moon. (This is a useful measure for me, in that my 8" telescope, at low power, can just barely fit the whole Moon in the field of view.) You will need to use a higher magnification eyepiece to see this pair as two stars.

.....If you can find Alkalurops (Mu Boötis), that will be much easier, and the two stars will be distinct as separate stars under even what is typically the lowest magnification lens for a given telescope, 1.8 minutes of arc (1/33rd of a degree, or about 1/16 the size of the full Moon) with stars of magnitudes 4.3 (can be seen on a good night, maybe not actually in a city) and 7.0 (invisible without the telescope/binoculars. I'll give you more once I have a chance to go hunting myself, until then, please don't hestitate to let me know what you like to see (or what you'd like my help to know about something you're seeing, in other words).

Not Dead!

2010-05-12T15:23:00.002-05:00

I just wanted to announce that this blog is not dead! After the demands of the school year choked it back last fall, this summer will see many, many (okay, maybe just "many") posts, with hopefully a large backlog to carry me through the winter. I will be focusing especially on people who might have gotten a telescope as a gift who is now taking it out as the nights start to get warmer ...

The Geminid Meteor Shower

2009-12-13T14:55:00.002-06:00

.....Tonight (Sunday, December 13th) is the peak of the Geminind meteor shower. This is one of the best meteor showers of this year (if it is not currently snowing where you are - sigh). The Geminid meteor shower comes from a trail of dust in the orbit of 3200 Phaeton.

.....This is unusual in that most meteor showers are due to the Earth crossing that path of a comet, and hitting (at about 60+ kilometers per second) the little pieces of dust that once, on some long previous pass, boiled off of the comet and helped reflect sunlight, resulting in the comet's bright tail. Phaeton is classified as an asteroid, not a comet, but it could simply be a comet so darn old that all of the ice (the shiny bit of a comet) has long since been evaporated by the Sun.

.....Looking for meteor showers is easy, as observational astronomy gets. Just go outside and get comfortable, and look in the general direction of east. Meteor showers have names due to the fact that they are all on pretty much the same orbit, so as the Earth moves through their path, the hits of the particles on the Earth (which heats them several hundred degrees in a few seconds as they burn up in the Earth's atmosphere) all seem to come from the same general part of the sky. In this case, the central point for these meteors is the general area of the constellation Gemini.

.....In the image that accompanies this entry, I have provided a view of the eastern sky from the northern US at about ten o'clock at night, to help you find Gemini. (Hint: start by looking for Orion the Hunter, one of three constellations that actually looks like what it's named after -- a big guy with a belt, sword, club and shield. These are also some of the brightest stars in the winter sky. We're going to come back to Orion soon for my series "So you just got a telescope", for anyone getting a telescope as a holiday present.)

.....The Geminid meteor shower has three things going for this year. First, the Moon is almost new, so the Moon will be providing absolutely no light to interfere with the meteor shower. Second, the Geminid shower has been very strong in recent years. One could expect to see up to 120 meteors per hour in perfect conditions, which, unfortunately includes being far, far away from city lights. Thirdly, the Geminid shower is one that is almost as strong before midnight as it is after midnight, so a little evening viewing should give you a view of some meteors. If the weather is clear, wrap yourself up warmly and give yourself a view!

.....(The peak is expected to be at about 11:10 PM CST.)

A Bright Space Station in the Evening

2009-11-08T12:43:00.002-06:00

.....As more is added to the International Space Station (from here on out, just the “ISS”), the space station can appear even brighter in sky on those favorable passes when the large solar panel arrays catch the Sun just right. Over the course of the next week , the ISS will make several passes over the continental United States in which it will appear substantially brighter in the sky than the planet Jupiter, the bright but relatively stationary light in the South. As I’ve written before, you can watch out for these good passages by combining trips to a weather website and one of several websites. (I use www.heavens-above.com, as I note in the links, and you can use the Messier Pro login and password as described in an earlier post.)

.....Oh, one thing that I have not mentioned is that these bright passes will take place in the early evening, and will be very easy to see. I took the opportunity to find a (hopefully) good night for a number of cities of friends, family, and a couple of people who have actually admitted reading this thing. I looked at the Weather Channel’s website, picked nights predicted to be clear, and noted the time and directions to look. I’ve put these in alphabetical order by state. If you’re state isn’t in here, then look at a nearby city, or drop a note in the comments and I’ll find a good time for your city.

.....This will be early enough so that even young kids can see it, so drag everyone you can outside, and then come back here and we’ll compare notes on who was able to see it!

Alabama (Mobile)

.....Yikes! What are you doing inside? The only decent pass for you this week will be this evening (Sunday, November 8th). If you go outside and look to the southwest at 5:11:06 PM, the ISS will appear over the southwestern horizon. The Space Station will be just south of directly overhead, and it will vanish just above the northeastern horizon at 5:17:52.
http://www.heavens-above.com/PassDetails.asp?Session=kebgfgclbbkemgcihfjooook&satid=25544&date=40125.9680109606

Colorado (Denver)

.....Hey, I’m sorry, but you don’t have a great combination. Go here, see you get anything, and then wait for a better week.
http://www.heavens-above.com/PassSummary.aspx?satid=25544&Session=kebgfgclbakbpkhgkmjkhfod

Florida (Orlando)

.....Yikes! What are you doing inside? (Not a lot of good passes for the gulf states this week.) The only decent pass for you this week will be this evening (Sunday, November 8th), and the ISS will only appear about as bright as the brightest star, but it should be visible in evening twilight. If you go outside and look to the southwest at 6:09:53 PM (the same pass as Mobile is seeing), the ISS will appear over the southwestern horizon. The Space Station will reach an altitude of 33 degrees above the horizon, and will hug the western and then the northern horizon until it vanishes into the Earth’s shadow at 6:17:15 PM.

http://www.heavens-above.com/PassDetails.asp?Session=kebgfgclbbkemgcihfjooook&satid=25544&date=40125.9684758333

Georgia (Lookout Mountain)

.....See Tennessee (Chattanooga). You live in Chattanooga, get over it.

Massachusetts (Boston)

.....It won’t be great tomorrow, but from 6:33;37 to 6:40:04, the ISS will hug the western horizon going north, disappearing due north, and never getting more than 10 degrees above the horizon.
http://www.heavens-above.com/PassDetails.asp?Session=kebgfgclbakbpkhgkmjkhfod&satid=25544&date=40126.9844423032

Michigan (the southwestern UP)

..... There are a lot of great passes, a lot of crummy weather. Try tomorrow night from 5:34:41 to 5:40:04. The ISS will rise in the southwest, appearing to be aiming due east. The ISS will only get 26 degrees above the horizon, and will still be 23 degrees above the horizon when it disappears behind the Earth’s shadow.

http://www.heavens-above.com/PassSummary.aspx?satid=25544&Session=kebgfgclbakbpkhgkmjkhfod

Minnesota (Elbow Lake)

.....Okay, really, this a great week for seeing the ISS from the upper Midwest. Minnesota has a lot of passes, and the best days for Elbow Lake will be tomorrow (Monday), but the best pass will be Tuesday. There will be two tries on Monday, the first going from 5:34:12 to 5:39:28. It will rise in the south and skim the southern horizon, moving to due east, never getting more than 12 degrees above the horizon. Monday’s second pass will be from 7:10:04 to 7:11:27. The ISS will be about as bright as the star Sirius, and as you can guess from the time, it won’t be up very long. The ISS will rise in the southwest and disappear behind the Earth’s shadow when it is 25 degrees above the horizon.

.....Tuesday is supposed to be partly cloudy, and you will see another pass of the ISS disappearing on the way. Rising in the southwest, the ISS will pass very close by the planet Jupiter as it moves to the eastern horizon. The ISS will get 31 degrees above the horizon, and disappear into the Earth’s shadow when it is still 20 degrees up.

http://www.heavens-above.com/PassSummary.aspx?satid=25544&Session=kebgfgclbakbpkhgkmjkhfod

Minnesota (Twin Cities)

.....Tuesday is the best day for all of Minnesota this week. From 5:09:08 to 5:16:27, the ISS will be the brightest object in the sky as it moves from the southwest to the northeast, getting 65 degrees above the horizon.

http://www.heavens-above.com/PassDetails.asp?Session=kebgfgclbakbpkhgkmjkhfod&satid=25544&date=40125.9680122685

Minnesota (Winona)

.....The clearest day on the forecast is Tuesday, which is also the day this week of the best pass. On Tuesday, the ISS will rise in the darkening sky in the southwest, rising high overhead at 5:56:15, reaching 67 degrees above the horizon, until it disappears into the Earth’s shadow at 18:02:08, still 34 degrees above the eastern horizon.

http://www.heavens-above.com/PassDetails.asp?Session=kebgfgclbakbpkhgkmjkhfod&satid=25544&date=40128.0007469907

Pennsylvania (Harrisburg)

.....Harrisburg has an exceptional pass today, from 6:14:45 until 6:17:52. The ISS will rise in the southwest, and pass very high in the sky before disappearing into the Earth’s shadow while it is still 66 degrees above the horizon. If you don’t make this, then your next best shot is on Saturday when the ISS will never get above 17 degrees over the western to northern to eastern horizon from 5:19:29 to 5:26:46.

http://www.heavens-above.com/PassSummary.aspx?satid=25544&Session=kebgfgclbakbpkhgkmjkhfod

Pennsylvania (Philadelphia)

.....Philadelphia has an exceptional pass today, from 6:14:47 until 6:17:39. The ISS will rise in the southwest, and pass very high in the sky before disappearing into the Earth’s shadow while it is still 66 degrees above the horizon. If you don’t make this, then your next best shot is on Saturday when the ISS will never get above 17 degrees over the western to northern to eastern horizon from 5:21:56 to 5:25:29.

http://www.heavens-above.com/PassSummary.aspx?satid=25544&Session=kebgfgclbakbpkhgkmjkhfod

Tennessee (Chattanooga)

..... Chattanooga should have good weather on Wednesday and Thursday, so on Wednesday (just after sunset) look from 5:35:46 to 5:51:03 as the ISS, as bright as Jupiter, travels from south of west towards the north, to set in the northeast. The ISS will pass about halfway up the sky, at about 39 degrees above the horizon.

.....Thursday won’t be as bright, but from 6:06:54 to 6:15:36, the ISS will skin the northern horizon, west to east, getting only 15 degrees above the horizon.

http://www.heavens-above.com/PassSummary.aspx?satid=25544&Session=kebgfgclbakbpkhgkmjkhfod

The Ghost of Mars

2009-08-27T11:23:00.006-05:00

Linguae centum sunt, oraque centum Ferrea vox. – Publius Virgilius Maro

[It (rumor) has a hundred tongues, a hundred mouths, a voice of iron]

..........In mythology, Mars has many followers: Phobos and Deimos (fear and panic, and the namesakes for Mars' two "moons"), Eris (goddess of discord, now associated with a ~~planet~~ Plutoid), and others. We must now add one more, the powerful demigod “Rerun”. (No, I don’t mean this “Rerun”. Or this one, for that matter.) Every August for the last few years, a email reappears on the internet, advertising how great Mars is going to look at the end of August. The emails going around often include claims that “Mars will be as big in the sky as the full Moon”, that “Mars won’t be this close again until 2258”, or that “Mars is closer than it has ever been in history”. So what’s up?

……… This email began in 2003, when there actually was a particularly close approach of Mars to the Earth. You may not remember Mars hanging in the sky like the full Moon; if so, don’t worry, you’re not crazy. Mars has a noticeably elliptical orbit, as I’ve shown in the first diagram. The Earth has an orbit that very close to circular. In the second diagram, the orbits of the Earth and Mars are drawn to scale in a way which emphasizes the oval nature of Mars’ orbit. Periodically (about once every twenty months or so), The Earth and Mars line up with the Sun, as the Earth passes Mars in its orbit. At this time, Mars appears larger than it otherwise would – but not by all that much.

……….To begin with, the closest approach (which is referred to as “opposition”, because the Sun and Mars will be on opposite sides of the sky) in 2003 was indeed close … but as big as the full Moon? The full Moon certainly dominates the sky, and seems to be huge against the celestial sphere, but actually the Moon is only about half a degree across. This means that you could stretch about 360 moons from one horizon to the other. For a angle smaller than one degree, we break one degree into sixty “minutes of arc” (this is the Babylonians’ fault – they liked dividing by sixty instead of ten), so the Moon has a size of about thirty minutes of arc. How large will Mars appear? Mars at its largest will not even reach one minute of arc, so lets go one size down and divide minutes of arc into “seconds of arc”, so that the Moon is 1800 seconds of arc (written as 1800”) across. Mars at its largest had an apparent size of 25”. Now, that’s pretty big – for Mars. We’re rather far away from Mars right now, and it currently has an apparent size of 5.8”; if you are willing to get up before dawn and look for Mars, you can find it in the constellation Gemini, above the constellation of Orion. It will be strongly red and fairly bright, but still dimmer than the two brightest stars in Orion. The chart below shows the sky at about 5 AM. The next closest approach will be at the beginning of next February, and Mars will appear to be 14” across. The claim that “Mars will appear to be as big as the full Moon” came from a claim in one of the emails that “Mars would appear as large as the full Moon when seen through a telescope”. The qualifying phrase fell out of the email quickly, which is understandable in that it doesn’t make much sense. It seems strange to say “the Moon is 75 times larger than Mars” in a way that makes it seem that you should be able to wave at Martians.

……….So, in 2003, Mars did appear larger in telescopes than it normally does, and it did appear brighter in the sky. I confess that I had no compunction about using the close approach to get the word out at that time; when we had a Mars viewing at where I was working at the time (Texas A&M University – Kingsville) had more than seventy people show up, some of whom came under the mistaken impression that they would never be able to see Mars again. Now, we’re just back in the zone where Mars appears every two years or so, large enough to show a disk when seen through a telescope

……….A lot of the confusion has been caused by the fact that the emails that had been clear and precise about Mars back in 2003 didn’t reappear each year, where the confusing emails remain. Kinda makes sense, though, since the precise emails would have had “2003” on them, and people wouldn’t be sending them six years later.

………Before I go, I have another confession: I’ve never really enjoyed observing Mars. Mars is only visible about once every two years, it does not have moons visible in a small telescope, it does not have rings, even at its closest it appears smaller than Jupiter in the telescope. Furthermore, Mars has a thin atmosphere, thick enough for there to be dust storms that can cover the entire planet, and thin enough for the dust storms to last for weeks, turning the planet into nothing more than an orange dot in the telescope. Ah well, I’ll give it another try next year, and see how it goes …

How did your Perseids go?

2009-08-19T15:22:00.003-05:00

..........Sorry that it seems like The Messier Pro has disappeared, but a family visit, two birthdays, an anniversary, and the beginning of the new school year have driven me to take a de facto vaction for the last two weeks. There are blogs that will be up soon on Ursa Minor and Draco, Bootes and Cocrona Borealis, and Hercules.

..........The viewing event that we had for the Perseids drew thirty people, although not as many Perseids as in previous years. Too a lot of people's surprise, the next night also had a large number of Perseid meteors.

http://apod.nasa.gov/apod/ap090817.html

The Perseid Meteor Shower

2009-08-06T09:21:00.012-05:00

..........The best laid plans o' mice and men aft gang aglee, and all that, and I am behind where I wanted to be with this blog, but if there is one thing that can bring me back with enthusiasm, it is the annual Perseid meteor shower.

(please click on the image to go to the source for the above photo)

..........Allow me to now take a step backwards. One of the romantic draws of the night sky is the unchanging nature of the sky. If you could step into a time machine and step out on the same night of the year during the time of the first dynasty in Egypt, the sky would appear the same as it does tonight. (Well, someone who has observed for years might -- and I emphasize the "might" -- notice a slight difference in the position of a handful of stars, and the sky would be darker because there would be no city lights, near or far, vomiting out photons to make sure we don't miss a Burger King or a Wal-Mart, and the sky would be turning about a noticeably different point ... but I digress, and that belongs to my discussion of the Little Dipper.) As far as the stars are concerned, the sky would be the same. Certainly, if you have done something outside with your parents the sky will be the same when you do it with your children. Even with this, the most notable occurrences are those times that act against a temporary screen against the "permanence" of the unchanging heavens. Comets, shooting stars, and the predictable motions of the planets tend to draw our eyes first, something that defines the now against a backdrop with an unchanging, uncaring nature. These things are personal, even friendly.

..........Meteor showers are also excellent opportunities to get more into astronomy, or intrduce more people to astronomy. My parents were very supportive of my astronomy, but it can be hard to pull someone out into the cold night to look at a fuzzy bit in a telescope -- after I had been able to find it. The Perseids, especially, were times that other family members came out. I have a lot of memories of going outside as a group to watch the Perseids, even one time going to a state park in Alabama to watch the display.

.........The planets move according to a predictable pattern, bright comets come and go usually as they are discovered; most bright comets are -- individually -- a once in a lifetime object, at best. Meteors (shooting stars), however, come by at about a half-dozen or so a night. Even in suburbia, a patient observer in a lawn chair can expect to see a few each week.

..........Meteors, as a whole, can be divided into three parts. Some fraction of meteors are bits and pieces of rock that never got swept up by a planet, little bits of flotsam and jetsam that have been floating around for a few billion years since the beginning of the solar system. Some are pieces from our spacecraft. NASA traces the motions of thousands of objects that could represent a threat to spacecraft, and when your speed is measured in miles per second, a small nut, bolt, heat shield, etc., can be pretty scary. I lived in central Florida for four years, thirty minutes south of the Kennedy Space Center, and it took a good bit of the romance away from meteor watching realizing that a lot of the meteors I was seeing weren't primordial gypsies, but bits and pieces of junk, haunting the orbits where they had originally been sent. (Without specifically applied energy, a satellite will continue to pass over its launch point.)

..........The third class of meteor originates in comets. When people think of a comet, the bright fuzzy head and long tail are not constant parts of the comet, but creations of the Sun as the comet comes too close. The Sun's energy causes ice, the primary constituent of a comet, to burst from the surface. The bright appearance that people think of when you think "comet" is due to the cloud of reflective ice the Sun forces off of the surface. The tail is ice and gas raised from the comet trailing behind the nucleus. After the comet has begun retreating out to the farther reaches of the solar system, that stuff doesn't disappear, but stays in the same basic orbit. The first few times that the comet passes by the Sun, the ejected dust, dirt, and associated grit stays in the same basic place in the orbit; some meteor showers, like the Leonids in November (more about that then) have big peaks aligned with the period of the comet (in the case of the Leonids, this is every 33 years). The Perseid meteor shower is the result of the Comet Swift-Tuttle, and this is old enough to get a good shower every year. The shower is also young enough to get a good shower every year -- the comet hasn't already seen all its component bits and pieces burn up in our atmosphere.

..........According to most sources the Perseids produce about sixty meteors per hour, but this (like much else) presupposed that you are observing this shower from dark site out in the country. If you are, great! If you aren't, you will see less, but any sort of sky should give you at least twenty meteors an hour on the night of its peak. (There will be meteors for several nights before the peak from this shower, but the meteors will fall off strongly after the peak on the morning of August 12th.) These meteors are called Perseids because they appear to come from a point located in the constellation Perseus (reasonable enough). The reason why is that the stream of particles crosses the Earth's orbit in such a way, and at such an angle as to seem to come from a small area on the globe of the sky.

..........Below is a map of the sky as it appears soon after dark for the first part of August (for those in the latitudes of the upper United States; if you are observing from someplace like northern Europe or Florida, there will be a minor change of perspective, some constellations will be higher or lower to the north/south, but it will be eminently usable). This is an attempt to take the inverted bowl of the sky and squash it down into something that comes more easily out of the printer. To use it, turn the sheet (presumably printing it out first) until the point on the compass at the bottom of the sheet matches the direction in which you are facing. The stars just above the horizon will be the stars at the bottom of the sheet. The constellation of Perseus is just rising in the northeast.

..........Here is the night sky a little after midnight, in early August. At this time, the number of meteors should pick up a bit, and they will tend to be brighter than before, because the Earth's atmosphere will be hitting the meteors head-on.

......... Something that I have none done successfully (so far) is to keep a diary, so to speak, of the Perseids. Using a red flashlight (to avoid ruining your ability to see at night), take a print-out of the sky and sketch the paths of meteors after you see them. If you hope to be out for some time, take several: use one for 10 PM to 10:30, one for 10:30 PM to 11, and so on. One sheet for an extended period of time for the Perseids might look like the one below. This also illustrates why they are named the "Perseids"; if you keep track of the meteors that you see on the night of the eleventh, most of them should appear to radiate out from a point in the constellation Perseus (the "radiant" of the meteor shower, naturally enough).

..........Good luck, and please stop back in and let everyone else know how your Perseids went!

Forty Years +1

2009-07-21T10:44:00.008-05:00

"The Earth is the cradle of mankind, but one cannot remain in the cradle forever" - Konstantin Tsiolkovsky

.........Yesterday was the fortieth anniversary of the Moon landing, the first of the only six times in history that humans have actually walked on another planetary body. I was a little less than two when this happened, and by the time my youngest brother was born we had left the Moon, and we haven't been back since.

.........There have been a number of responses that I have seen to this fact. One of the drives for reaching the Moon was to "win" the space race against the Soviet Union. Once this was done, this part of the impulse was gone. We had already run this race, why stand around at the finish line instead of going out for pizza and beer? (That would be "root beer" if you're under twenty-one.)

..........Ratings for even the second Moon landing were well below that of the first, and it seemed as if there was no enthusiasm among the general population for more Moon shots. The Lunar program was also seen as a Democratic program (the landing was just six months after Nixon's inauguration), and it might have suffered from this view under Nixon and Ford. After Apollo 17, the space program turned to the shuttle, seen as preparation for a next step, but which seemed to become its own destination. Even the space station has been its own end. What next? Are we as far as we can go? Are we as far as have the will to go?

..........Another question that is asked concerns our use of resources, and this is certainly not an idle or non-compelling question, especially now. What could we do with the money that space exploration or NASA in general uses with people in poverty, desperate need of health care, and the job market dropping like the morale of a football team once Terrell Owens signs up?

..........Also, we must consider the question of priorities, even if we can assume that amount of money going into space science. Is it good to fund manned missions, or should we use the same money to fund a number of smaller efforts, in which a greater number of people can take part?

..........All of these questions demand a good answer, and I will even go so far as to say that in order to support more manned missions, an argument must be made that justifies a program against all of these points. Can a space program do more than just beat "the enemy" somewhere, and produce more in the public imagination beyond Tang (TM)? To make this argument, I want to make a wider claim about what the Moon landing provided.

..........Consider the object shown to the left. What is the value of this? Is this simply a waste of good marble that could have been ground up and used as the basis for houses, sewers, roads, etc? Is the value of this equal to the value of the material that makes it up, or the use to which the material could be put? I will venture to say that most people would say "no" to the last few questions, to acknowledge that art as a human creation has a value in the act of cultural, human expression. That beyond the day to day needs of basic human existence, we have a need that is higher, to make a higher purpose, a reason why we are here, a calling to others to acknowledge something even higher to which human beings can aspire. Even art taken as entirely secular still speaks to the fundamental human desire to define meaning for ourselves, to create ourselves as some thing above day-to-day existence. The Moon landing also made the argument that human beings can create a meaning for themselves in an even wider fashion. The statue I picked was the work of one man's genius, but the Moon landing required scientists to plot the way there, engineers to create the materials we needed to get there and back, and what we needed to keep people alive on the trip, people brave enough to risk everything on the say-so of people who had never done this before and the skills to handle what could come up, and taxpayers.
..........Lots of taxpayers. On the other hand, this enabled everyone in the country to take pride in and ownership of the Moon landing, and justifiably so, in my opinion. This, I would say, is something that we need again now.

..........When John F. Kennedy called for human exploration of the Moon, the United States was in an excellent position to commit ourselves to a great leap, a tremendous effort that we could do because the US was at the zenith of its power. The recovery of the rest of the world, directly affected in World War II, was still at the point where they were a tremendous market for the rest of the world, and had not yet returned to the production capacity that the rest of the world had before. Today is drastically different, but a space program with a clear human goal of a sustained presence on the Moon or a trip to Mars could restore not military leadership, not technological (though it would help) leadership, but leadership of vision. I can most honestly speak of this in terms of what the space program meant to me.

..........What did the landing on the Moon mean to me? I didn't gain an interest in astronomy when I was one and a half, but over the next few years I do remember watching the astronauts returning to Earth, and being recovered by aircraft carriers (yes, Keith, I know those were SEALs), and I can remember my amazement at considering that people, actual people, were capable of firing a rocket (essentially a big, controlled bomb) off from the Earth, using it to send people into space, and then being able to work out where they would come back with such accuracy that there could be ships waiting right there to pick them up. As the seventies aged, I saw a rush of people for magic, whether it was transcendental meditation, astrology, weird new medical fads in which people hoped for some way of cheating of the universe, some way of the controlling it to get the result they wanted. I was not brought up to be "afraid" of math, as if math was some magical field that only special people could do, so even at seven I was confused about why people would turn away from the examples of all the best that we could do to trust in something with no results, but which felt nicer, as if you could ask the universe for something, and how much you believed, or how nice you were actually counted. People have even sidestepped what human beings can do to hope to jump past them, to imagine aliens visiting the Earth who will solve all of our problems if we just ask them nicely enough.

..........There is no evidence of that ever happening, and no evidence of any magic, or any space cavalry to come riding over the hill and save us from the problems that we made for ourselves. All we have is us. We have problems that we cannot solve simply by saying, "I'm fine; let each person solve this independently." We have problems that cannot be solved state by state, and now even nation by nation. As we need to work together (not *under* each other, but as a collection of individuals/localities/states/nations) we should have something that will give us an experience of true greatness, something that needs all of us to work together, and shows us that we can do what seems impossible, to give the renewal of will and the hope that our more tractable problems like disease, poverty, hunger, etc., ad infinitum, are within our reach themselves.

Ursa Major (part 3 of 3)

2009-07-17T10:52:00.004-05:00

Messier Objects in Ursa Major

.........Wednesday night I was fortunate enough to have a wonderfully clear night, so I was able to double-check all of my impressions of the appearances, the methods of finding Messier Objects, and the maps that I have made for this purpose. Each of the Messier objects will appear with a star map showing you how to get from a bright (well, fairly bright ... well, identifiable) star to the object. Each map will be on a different scale -- some objects are close to bright stars, and some require more of a trip. On each map will be indicators matched to the field of view of common telescopes. If you can fit the entire full moon in the field of view of your telescope, then you can use my circles as good guides as to the sizes of the steps that you are going to have to make to get where you need to go.

..........Because of the name of the blog, my first pass through the sky (the first year of the blog) will cover the Messier objects, constellation by constellation. (For most constellations, I’ll be able to do this in the same entry; the Big Dipper is unusual.) There are seven (eight) Messier objects in the area of the Big Dipper, and I’ll cover them in numerical order. This is a bit unfortunate, because the first Messier object on the list, the first Messier object I’ll cover here, is …

M 40: The Lamest Messier Object of Them All …
Difficulty Level: 2 (Close to a bright star, only one jump.)

.........Because M40 is the lowest-numbered Messier object in the first constellation I’m talking about then this is the first one I’m covering, which is a bit unfortunate, all things considered. Responding to the report of Johann Hevelius, who claimed to see a nebulous patch in this area, Charles Messier attempted to find the object at the location the other astronomer gave, only to discover nothing at all. It’s quite possible that the original observer actually did see a comet but didn’t recognize it as such, and recorded it essentially as "gunk that gets in the way of identifying comets".

..........For some reason, Messier felt the need to identify something in the area with Hevelius’s observation, so a double star was identified as “M40”. (As it turns out, this even isn’t a double star, but simply two stars along the same line of sight.) If you would like to find this “object”, the path is easy enough. Start with d Ursa Majoris (Megrez), the star connecting the handle to the bowl. Just above Megrez is a triangle of stars that should all appear easily enough in your finder scope or binoculars, which leads me into a bit of an aside, since this is the first example of star-hopping that I'm using.

........When mapping a way from a bright star to a fainter object of interest, I’ll use patterns of stars (asterisms) to help fix the image in memory, but in this case I was a bit put off because it is a little hard to make anything besides a triangle from three nonlinear stars, but inspiration has struck, and I will name this asterism “the Snark”! (I'll explain this in just a second.)

.........To find M40, which I will therefore name “Boojum”, find the lowest star in the triangle (the one closest to Megrez) in the eyepiece, and the optical double which has inherited the name M40 will enter your field from the north if the star (which has the name 70 Ursae Majoris, unless you have a better name for it) is moved to the southern edge of your field. The Boojum is one of the easiest Messier Objects to find, and (sadly) one of the least interesting. Okay, it is the least interesting Messier Object.

.........Why does the substitute for a disappearing Messier object get named “the Boojum”? I took this from Lewis Carroll’s poem, “The Hunting of the Snark”.

" 'But oh, beamish nephew, beware of the day,

If your Snark be a Boojum! For then

You will softly and suddenly vanish away,

And never be met with again!'

.........To help you get an idea of the brightnesses of starts seen through the telescope, the two stars that are The Boojum are ninth magnitude (9.0), about the limit of stars in the smallest telescopes. It will be good to use this to get an idea of how easy it will be to find other Messier objects, ones that are a lot more interesting.

M 81 and M 82: "I'm not touching you, am I bugging you?" Galaxies
Difficulty Class: 3 (Some jumps through asterisms)

.........To my mind, the jewels of the Big Dipper are the two nearby galaxies (near to each other, and relatively close to the Milky Way) M 81 and M82. From my point of view, these are some of the easiest galaxies to find, although you may find differently. These were some of the first deep-sky objects that I learned to find, so the asterisms that I use to find them might not appear to be as obvious to you.
Start at the end of the Dipper bowl (the star Dubhe), look north of Dubhe, and a bit to the west. In less of a shift than it would take to go from Dubhe to Merak, you will find some stars that appear to me to be a mirror-reversed Greek letter tau. Since I’m printing this on a map instead of just trying to remember a path at the telescope, I am naming this the asterism "The Chickadee". Once you’ve found this, center the Chickadee in the center of your binoculars/finder scope. If you now go due north, you’ll find what I call the broken arrow (this one needs a better name – any ideas?) : a triangle of stars that appears to me to be the back end of the arrow, which can be traced east to a star with another star of about the same brightness off the line, giving to me the appearance of a broken arrow. Visible in binoculars or a telescope’s finder scope as two faint fuzzy patches about two-thirds of the way closer to the break in the arrow than the fletching are the two galaxies we are looking for. (If you can’t see the galaxies in a finder scope, just aim for a point along the line of the arrow and hope for the best. (As always, if you don’t see the galaxies in the telescope then unlock the telescope and search in increasing circles from your starting point. Never underestimate the importance of patience in astronomy.)

..........M81 and M82 are reasonably close (as galaxies go) at a mere twelve million light years away. These galaxies appear close together in the sky because, in this case, they actual are close to each other – and they used to be closer, which affected in ways even visible now.

M81: Bode’s Galaxy

.........M81 was first discovered by Johann Elert Bode in 1774, and is often called "Bode's Galaxy". The total brightness of this galaxy is magnitude 6.9, implying that the object should be fairly bright, but this can be misleading. By luck, I started this so that the final constellations that I talk about will be constellations with a lot of galaxies. This is lucky because galaxies can be some of the hardest objects to observe. In stars, including clusters of stars, we’re looking at a lot of point sources of light – even with streetlights, moonlight, etc., clusters can still be seen. In galaxies and nebulae, the light is smeared over an area; any increase in the background light can drown out the image entirely.

..........Bode’s Galaxy is a fairly reliable target, a face-on spiral galaxy will two bright arms. It will appear as a bright smeared dot of light, and on the very clearest and darkest of nights, the two spiral arms of M81 will be visible as well.

.........I have an anecdote about Bode's Galaxy that I now feel compelled to share (otherwise, you ould just skip to the next paragraph.) In 1993, a supernova was observed in M81 and, as these things do, for a few weeks that one dying star gave out as much light as the rest of that galaxy. This made a lot of news, as there is lot of physics and astronomy that we can learn from supernovae, plus it was cool to watch. At that time, I was living close to Cape Canaveral, and had the opportunity to watch a night launch of the space shuttle. I had brought my telescope to the launch site to get a close view of the shuttle, but after a while of counting heat tiles, I began to get distracted. On a whim, and not expecting very much because we were surrounded on all sides by brilliant streetlights, I aimed the telescope at Dubhe, and moved the scope about as far as I remembered it being to the west, and then north, to get to M81, and looked in the telescope. By some astounding quirk of luck (although I tried to pretend that it was skill), I could see the field with M81 in the telescope! The galaxy was invisible due to all of the background light, but the star field plus the supernova was recognizable. There, my secret is now out.

M82: The Starburst Galaxy / Cigar Galaxy

.........With M81 in the center of the field of view, one can move the telescope so that M81 moves to out of the southern edge of the field of view, and then move the telescope gently along the other axis, and M82 will appear, a thin jagged line of light. The Starburst Galaxy is an irregular galaxy that can almost fit in the same field of view with M81. Galaxies are divided into four major groups: spiral galaxies, barred spiral galaxies (a spiral galaxy with a bar structure in the core), elliptical galaxies, and “irregular” galaxies, galaxies in which something has happened to distort the shape of the galaxy. In the case of M82, this was a close pass, in which M81 caused a lot of the gas clouds in M82 to collapse into new stars. More recent studies show that M82 is probably a barred spiral galaxy seen edge on, with the burst of new star formation somewhat hiding the shape.

M 97: The Owl Nebula m = 11.20
Difficulty Level: 5 (close to a bright star, but individually quite faint.)

.........I’ve found the Owl Nebula one of the hardest Messier objects to find in the sky. At a total visual magnitude of 11.20, and that is considering all of the light concentrated at one point, which it most certainly does not. I wouldn’t advise looking for the Owl Nebula on anything but clear, moonless nights.

.........The Owl Nebula is a planetary nebula, made up of a rough bubble of gas ejected from a star as it goes into "retirement", casting off its outer layers and becoming a white dwarf. A planetary nebula is an expanding cloud of gas, so it has a limited lifespan, until the cloud gets to diffuse to see, or too far from the central remant of the star to shine in absorbed and reemitted light. this puts a clock on it of about one hundred thousand years. A long time as far as library fines go, but nothing on the time scale of stellar existences. There are therefore relatively few planetary nebulae (only four in Messier's list), and this is the hardest to see.

M101: Didymus

m = 7.70
Difficulty Level: 4 (Easy star hop, individually faint)

.........This galaxy is a large, face-on spiral, quite an impressive sight that will even allow you to see the spiral arms, but the night has to be pretty much perfect. On my excellent viewing night this week, I was able to star-hop to the correct field, and see all of the stars that I was supposed to see, but there was no sign of the galaxy. Stuff like this gave rise to my third law of living, "You can do nothing wrong, and still lose."

.........Messier 101 was named "Didymus" (by me) because it is its own twin, of a sort. Charles Messier recorded this galaxy as M101 and later recorded the same galaxy as M102. In the case of M40, Messier found something nearby and get it a number. In the case of the galaxy M91, in Virgo, Messier recorded a non-comet at a position where nothing was later found, and the number was simply assigned to another galaxy nearby that was bright enough to have been seen by Messier, but was otherwise unrecorded.

M108: Galaxy
m = 10.10

.......... Both M108 and M109 are faint spiral galaxies that are difficult to observe when the night is not completely dark, and the sky is not completely clear. M108 can be found on the same star map as M97.

M109: Galaxy
m = 9.80

..........Both M108 and M109 are faint spiral galaxies that are difficult to observe when the night is not completely dark, and the sky is not completely clear.

Difficulty Level: 4 (Easy star hop, individually faint)

Ursa Major, Part 2 of 3 (Blog #4)

2009-07-05T21:50:00.008-05:00

“Thou art as opposite to every good
As the Antipodes are unto us,
Or as South to the Septentrion”

Henry VI, part III Act I, scene iv, lines 134-136

.........The first and last stop on our year-long tour of the constellations (at least the ones that can be comfortably viewed from mid-northern latitudes) will be Ursa Major. To be more familiar, I should be referring to Ursa Major as the Big Dipper, an asterism of the seven brightest stars in the constellation. (An asterism is a recognized pattern of stars that is not itself a constellation. In some cases as we will see later this summer, an asterism can include stars from more than one constellation.) I am following tradition in this as all of the early catalogs began with Ursa Major and Ursa Minor (again, more commonly recognized by the Big Dipper and Little Dipper).

.........The stars of the Big Dipper have been recognized as a constellation from the earliest times. Homer seems to have recognized the Big Dipper (as a bear) as the only circumpolar constellation as “Arctos, sole star (here taken as constellation) that never bathes in the ocean wave” The Big Dipper appears in the Bible, in the book of Job “He [God] made the Bear and Orion, the Pleiades and the constellations of the South (9:9)”, and “Can you bring forth the Mazzaroth in their season, or guide the Bear with its train (38:32)?” Note that the Dipper is not represented as a bear with an incongruously large tail, but as a bear with three followers (cubs? hunters?). (It is unknown what Mazzaroth represents. It could refer to a southern constellation using the pattern of parallelism in Hebrew poetry, or it could represent the zodiacal constellations as a set. It could also represent a handy gardening tool with a built-in mulching attachment; we just don’t know.)

.........In addition to being such an easy asterism to find in the sky, and in addition to leading the viewer to a number of other bright stars (hey, you have to learn the sky starting somewhere), the Big Dipper is one of the oldest constellations. I feel that I’m being fair in saying “the Big Dipper” here, as opposed to “Ursa Major”, because “Ursa Major” itself is an expansion of the Big Dipper. Sure, it was an expansion that took place several hundred years BCE while the other circumpolar constellations were created at this time, but the Big Dipper was old even at this time. It is impossible to know just how old, but the idea of the Big Dipper as a bear is surprisingly widespread, in bold defiance of the fact that it looks nothing like a bear. (The idea that Ursa Major is old enough to go back to a time in which bears looked a lot more like dippers has, unfortunately, little evidentiary support.) The writer Thomas Hood took a different tack:

“Imagine that Jupiter, fearing to come too nigh upon her teeth, layde hold on her tayle, and thereby drewe her up into the heaven; so that shee of herself being very weightie, and the distance from the Earth to the heavens very great, there was great likelihood that her taile must stretch. Other reason know I none.”

.........Our constellations are (largely) the Latin names of Greek constellations, many of which were taken from Babylon and India, so overlap here is highly unsurprising. Admittedly, the Germanic nation did not consider this a bear, but a wagon (which makes sense, seeing the bowl as the wagon and the handle as the bar that the animals would be attached to); what is surprising that a number of North American cultures also saw a bear here. (To their credit, they only saw the bowl of the dipper as a bear; the three stars of the handles were hunters chasing the bear, catching it in the fall when the bear, low in the evening sky, would drip blood onto the trees, changing their colors.

.........There has been some conjecture that the Big Dipper is the remnant of some Paleolithic bear cult, but this might be reading too much into this. Beyond the elephant, the bear is the largest land creature, so the most important group of stars is probably predisposed to be called “the bear”. If there is anything to the idea that the Dipper was considered a bear even before the migrations to America, it might be as William Whitney (American philologist of the nineteenth century) supposed, looking at how the Sanskrit word Riksha can mean either “star” or “bear”, depending on the gender of the word. The seven most important stars in the sky could then have been the "seven bears", or just eventually lumped together as "the bear". Or, maybe a North America culture just picked "bear", and the constellation name spread. There is currently no way to know.

.........I was considering also discussing the number of times that different constellations appear in literature, but starting with the Big Dipper made this prohibitive, since references to it are so common. Perhaps my third pass through the constellations can cover its literary lights (see you in 2011). I'll tell you what: I'll cover the Bible, Shakespeare, Dante Aligheri, and Homer, and ask the gentle reader to take the rest. If you run across a literary reference to a constellation, please let me know. (I'll cite you -- you're name will be in a blog ... wow!) I did find three appearances of the Big Dipper in Shakespeare as well. In addition to the quote that begins this entry (the Septentrion, or “seven stars” is the Dipper), the Big Dipper is also referenced in Henry IV, Part I, where it is used as a timepiece (I'll discuss this more when we talk about the Little Dipper, and using the stars to the north as a clock) and a reference in King Lear where Shakespeare has one of the villains of the piece speak in what we would now consider to be enlightened skepticism about astrology. I'll go into more detail on this when I talk about the first zodiacal constellation on our tour -- Ophiuchus! (Don't recognize this as apart of the Weekly World News zodiac? I'll explain soon ...)

.........In this post, I'll speak about viewing Ursa Major with the eye, and add in binoculars and telescopes in the next blog. I have discussed in a previous blog entry how the two stars at the end of the bowl, Dubhe (which comes from its title as the back of the bear) and Merak (which comes from its title as the loin of the bear) can be used to find the North Star, Polaris. There are several other bright stars that can be found using the stars of the Dipper as well.

.........Confining ourselves to the stars of the constellation itself, take a look at the center star of the handle, the bright star Mizar. Mizar has a magnitude of 2.23, a fairly bright star. Close to Mizar in the sky, close enough to be seen with the eye, if your eyes are good, and easily with a pair of binoculars, is a fainter star, Alcor. Alcor has a visual magnitude of 3.99, which means that we are receiving about five times as much light from Mizar as we are from Alcor; we don't see Mizar as five times as bright, because our eyes don't work such that twice the light equals twice the brightness. If that were true, then your head would all but explode as you went inside and turned the lights on after being out looking at the stars!

.........Mizar and Alcor are separated by a distance in the sky that is about 1/3 the apparent size of the Moon in the sky. Many cultures have used this star as a test of vision, requiring a reasonably sharp eye to see this as two stars and not one. There has been a question as to whether Mizar and Alcor are actually part of a double star system, or if the are simply close to the same line of sight in the sky. This is somewhat similar to seeing two people sitting together on a bus and assuming that they are married. It does seem that these two stars are indeed orbiting each other, but widely separated. The closer star, Mizar is about 78 light years away, which means that the light you see tonight left the star's surface in early June in 1931, and has spent all that time traveling through space. Alcor is about three light years away from Mizar, or about 190,000 times the distance between the Earth and the Sun. If these stars are orbiting each other, it will take about 43 million years for each orbit. Mizar is itself a double star, but you will need a telescope to see that. Both stars are about the same brightness, and much closer. They orbit each other in only about 104 days, a much smaller separation.

........The next post will take us through Ursa Major with binoculars and telescope, and we will see if we can then move on to another constellation.

SPECIAL ADDITION: Check out this link!

Ursa Major, Part 1 of 3 (Blog #3)

2009-07-01T08:43:00.013-05:00

Before we get started …
..........This entry is much later than I had hoped it would be, and it has grown into quite a monster in the meantime – I promise, this is larger than the standard entry will be, and much more space than the average constellation will get. Heck, I had to break Ursa Major in three parts! This is part I, "Ursa Major As a Guide to the Sky". The next two will be "Ursa Major, the Constellation" and "Ursa Major, Telescope Stuff". Posting frequency will drop to (probably) once per week in the fall, but I want to post more frequently in the summer. For example, I hope to finish Ursa Major this week.

Downloading
.........Much of the writing time between posting was directed to working out a way to make star maps that were done entirely by myself, so that I could replicate them as I would. However, once I post these as images, much of the detail gets lost; to correct this, I have uploaded the image files to a Google discussion group. (If you choose, you are free to ask questions about the blog, certain topics, or things that you would like to see there, but I would appreciate if you would comment about individual blogs in the space after the blog entry.) There, you may download the images to get maps that I hope you might find useful.

My Starting Point
.........There is ~~method~~ luck to my madness, as I begin at Ursa Major. Let us start with the Big Dipper, the most recognizable part of Ursa Major. The Big Dipper makes a good starting point because for most of America, it is a circumpolar constellation; that is to say, the star is close enough to the pole that it never sets below the horizon, and so it can be seen all year long. I will continue on into summer constellations, in which most of the things that binoculars or telescopes will lead you to are clusters of stars, which (as collections of points) can still be seen on moonlit or suburban nights. This will lead us through the year, ending with the constellations of spring, which have many galaxies, some of the most difficult deep-sky objects to observe. So, if you want to get into astronomy (or deeper into astronomy) summer is a good time to start (if you can stay up late enough to chase twilight). I’m starting with the Big Dipper because it is one of the most recognizable patterns in the sky, and one of the easiest to find. In June skies, the Big Dipper will start the night near the zenith (directly overhead) , and in July the Dipper is still high in the northwest by 11 PM.

Naming Stars
.........The Big Dipper can also serve to introduce how stars are tracked individually as well. Of all the stars that can be seen with the naked eye (there are slightly more than 5,000 as the HIPPARCOS satellites saw it), there are about two hundred that have individual names. These are typically the brightest stars in a constellation, and show the limits of the usefulness of designating stars individually in such a unique manner; after all, could you reliably remember five thousand names? (Heck, have you ever had to correct a grandparent or other family member? Odds are, there aren’t five thousand in the family.) Here is a star map of Ursa Major with all of the named stars shown: (at least, before people start claiming stars to name themselves.)

.........Another method was derived by Johann Hevelius in a star atlas published in 1603. He tried to name the brightest star in a constellation “alpha of that constellation”, so the brightest star in Ursa Major should be a Ursae Majoris (then b, g, d, and so on). Ursa Major is an unfortunate starting point for introducing this system, because in this case, as you can see, Hevelius simply started by making a pattern of the Big Dipper. Here is a map of the Big Dipper with stars named in this system:
.........The stars of the Big Dipper can also be used to provide a sense of scale across the sky. Judging scale is one of the biggest problems in getting used to moving around the sky, because in the sky there are no points of reference that we see on the ground. Fortunately, we have fairly reliable measurement tools at the end of our arms – we can use our hands. (Yes, your hands are almost certainly not the same size as mine, but your arms are also differently sized than mine as well. This balances out.)

.........Consider the “distance” between the stars Dubhe and Merak. I put the word “distance” in quotes, because we have to define what we mean by distance. If I describe the physical distance as 45 light years, how does that help you? We’ll use “distance” to refer to the angular distance between two things in the sky, so that an object on the horizon due north will be 180⁰ away from an object just above the horizon due south. In this way, the distance between these two stars is just a little bit more than five degrees. As shown in the diagram below, this distance against the sky is about the same as the angular size of three fingers held at arm’s length. This can also be used as an order to your bartender if the viewing isn’t good. (PARENTS: If you little one comes in, sighs, and says, “Gimme three fingers of Redpop”, then s/he has been reading this blog.)

.........The stars Dubhe and Phad are ten degrees apart. This is about the distance between your fingertips is you extend your hand as shown below, a form that is either reminiscent of a certain arachnid-based superhero from a company with “marvelous” lawyers, or – if you were a young person in the 70’s or 80’s – the “secret devil sign” beloved by metal bands and freaked out middle-aged PTA moms. Of course, if a freaked-out PTA grandma sees you making a devil sign to the night sky, then you might need to refer back to the “three fingers” – once the police leave.

.........The stars Dubhe and Alioth are fifteen degrees apart, which can be measured by the hand sign below, which I have christened the “dude”. (Pronounced “duuuuuuuuude”.)

.........The Big Dipper can also be used as a guide around the sky as well. A line that passes through Merak and Dubhe will pass very close to the North Celestial Pole, and hence, the North Star. (This is helpful, because while the North Star Polaris is a reasonably bright star, it is nowhere near the brightest star in the sky, though this is a common misconception.)

.........A line passing through the other end of the bowl will come very close to the bright star Regulus, in Leo. This star is setting very close to sunset now, carrying Saturn with it into daylight anonymity.

.........If you follow the curve of the Big Dipper's handle, the curve will arc towards the bright star Arcturus, in Bootes (coming soon), and if you go past Arcturus, you will speed on to Spica, in Virgo (next to last of this series, next spring).

........Get familiar with the Dipper and the stars around it, and I'll be back to write about the stars of the Dipper itself, and a famous test of vision across the ancient world.

A Constellation Preview (Blog #2)

2009-06-20T15:36:00.005-05:00

Looking at the images I posted from my last blog, I can see where I need to find better ways of making images, so I have worked on that. I have also been working on a way to plot the constellations that does not involve copyrighted material. I think that I have succeeded in this using the data from the HIPPARCOS satellite, Microsoft Excel, Microsoft Paint, and coconut shells. As an example of the result, here is an image from the next post, the first post on the constellations, a map of Ursa Major (including the Big Dipper) with named stars.

Now if I can only find a way to make the image display with the detail that I want it to show ...

The Planets Right Now (Actually Saturn, Saturn, and More Saturn) (Blog #1)

2009-06-18T23:08:00.008-05:00

PREFACE: I’m going to rely more strongly on sketches I make at the telescope than on photographs, because photos can be a lot cooler than what you can see with eye – the photo can be taken over a long period of time, and reveal colors and structures that we can’t see by eye. This is actually one of the complaints that I have about a number of observing aides; by showing photos with more details than the eye can see, a visual observer could be greatly discouraged instead of being able to learn to see what is there. Happily, planets do not have that problem. Planets are so comparatively bright that sensitivity is not a problem, and in fact the eye does a better job than most non-spacecraft cameras for seeing details on the planets. Plus, there are some really cool planetary images in the public domain.

The primary purpose of my blog over the first year will be discuss each constellation visible from the continental United States in turn, with special emphasis to the Messier Catalog, Charles Messier’s list of 110 galaxies, clusters, nebulae, and … stuff. (I’ll explain that in my first constellation post on Ursa Major – the Big Dipper and more). I’m not just going to be doing that, because I want this to be interesting for anyone who might just be starting a relationship in the night sky.

Some of the easiest objects to find and watch in the sky are the planets, and there is a good reason to have a post about where the planets are right now (and what they are doing), and that brings us to the first planet we will look at, Saturn. Saturn is the sixth planet out from the Sun, and the second largest planet, but the aspect of Saturn that everybody rightfully thinks of is its ring system.

The rings of Saturn are so bright because they are largely made of ice particles, and the diameter of the ring system is over one hundred and twenty thousand miles across – but the rings are only a few miles thick. We can see the rings of Saturn because Saturn’s orbit is tilted slightly compared to the Earth’s, but even with a tilt, there are still two times during Saturn’s orbit around the Sun at which Saturn is in the same plane as the Earth and we look at Saturn’s rings edge on. At these times, the rings seem to vanish altogether! The next time this happens will be in late September, but Saturn will be too close to the Sun to see, so go ahead and look now, if you have even a small telescope, to see Saturn’s rings as a narrow line.

(The disappearing rings were noted by the first person to look at Saturn through a telescope, Galileo, who only saw indistinct shapes on Saturn’s sides. In Greek mythology, the titan Cronos – associated with the Roman ‘Saturn’, although that isn’t really … but I digress – who swallowed his children as they were born to thwart a prediction that his child would supplant him. When Galileo saw “Saturn swallowing his children”, he was so frustrated that he stopped observing Saturn at all.)
Saturn can be found in the west as night falls, south the constellation of Leo. If you are looking above the western horizon, the map below shows you approximately what you would see, without the names and big blue lines. If you have any city lights in the vicinity, then you might just see the stars whose names I have included.

If you want to be sure if you are recognizing the stars correctly, I have included a map from my first constellation blog showing some of the stars that can be found from the Big Dipper. If you can find the Big Dipper high in the sky, then you can follow the two stars of the bowl that connects to the handle along a line that comes very close to the star Regulus.

That’s all we have in the evening, but if you are actually getting up early some morning to look for the space station, or if you just have a time when you can’t sleep, the planet Jupiter (the fifth planet, and the largest planet in the solar system) will be high in the southern sky, and Jupiter will be by far the brightest thing in the area. If you were to look at Jupiter in even a small telescope, the four largest moons of Jupiter (on the same size scale as our own Moon) will appear as a line of stars. The planet Neptune (the eighth planet, about four times the radius of the Earth) is actually very close to Jupiter in the sky right now. If you are able to find Jupiter in a telescope, and you can tear yourself away from the view of the moons, and the bright bands and dark zones of Jupiter’s cloudtops, then you can try and find the planet Neptune to the north and east of Jupiter. Neptune is fainter even than the moons of Jupiter, and shows you as little. While telescopes will show the disk of the planet Neptune, and you can see the strong blue color caused by the methane clouds of Neptune’s atmosphere, that’s all that you get. No matter how strongly you magnify that image, neither Neptune nor Uranus (a little harder to find) will show any features whatsoever. Mark off that you have seen Neptune (hurrah!) and go back to Jupiter.

Uranus is much harder to find, located in the constellation of Pisces, which has no bright stars to speak of. I’ll go into more depth in finding Uranus when it becomes more of a evening star.
Venus and Mars are both morning stars right now, visible in the east before sunrise. Venus will be high enough in the sky to find easily. From Venus, Mars is close to the north, and both should be visible in the same field in binoculars. Mercury, the last planet to rise tonight, will rise shortly before the Sun, and would be very, very difficult to find.

(I’m waiting to get into the whole Pluto thing til its own entry. Pluto is up tonight, but forget about seeing it. My own telescope is too small to see Pluto, and even if I could, it would only appear as a dot. Really, this blog is about Saturn.)

Glossary (Blog #0)

2009-06-18T22:58:00.002-05:00

In this “zero-eth” Messier Pro, I am just going to define a few terms that you might not be familiar with unless you’re already familiar with amateur astronomy. I’m going to post a link to this on the side of the page, and I will come back and add to this glossary as I keep finding things that I forgot to define …

ASTERISM:
An asterism is a pattern of stars that is not a CONSTELLATION (which see). I’ll make up patterns of stars to help find some objects off the beaten path, and I’ll introduce some identified asterism as we go.

BRIGHTNESS:
Brightness describes how an object appears from Earth, and so doesn’t actually say anything about the object itself. There are stars that are bright because they are close to us, and stars that put out much more light, but are dimmer because they are farther away.
Brightness is measured in magnitudes, in an idea going back to the Greek astronomer Hipparchus. Hipparchus labeled the brightest visible stars as “stars of the first rank”, and the dimmest stars as “stars of the sixth rank”. Tradition is a powerful force, and this has remained the pattern even as we now have technology able to measure just how much light is coming off of a star. The faintest stars that can be seen with the naked eye (see “named stars”) are sixth magnitude, and first magnitude stars are some of the brightest stars in the sky. The magnitude system is not linear because the eye’s response is not linear. The system is defined such that a star with a magnitude of m = 1.00 provides 100 times as much light as a star with m = 6.00. This means that brightnesses can be unintuitive to the point of frustration. The brightest star, Sirius, has a magnitude of -1.4, the planet Venus can get as bright as -4, and the Sun has a visual magnitude of -26.

CONSTELLATION
A constellation is an arrangement of stars that has long been considered to represent some figure or object. Most cultures had their own set of constellations (some cultures named individual stars, some probably had their own but got culturally co-opted by some other group), but the “official” set was settled upon by the International Astronomical Union (the same people who disqualified Pluto) in 1930 based upon the Roman constellations taken from the Greeks, some of which they took from the Babylonians, Indians, and more. There are 88 accepted constellations.

DOUBLE STAR
A double star is a system in which two stars are actually orbiting around a common center of mass. There are many sets of double stars that are close enough to Earth to make interesting things to see, there are some that are interesting because the orbits of the two stars actually cause them to eclipse each other as seen from Earth, and there are also some stars (called “optical doubles” that have been identified as double stars, but were later discovered to have simply been in the same line of sight, and nowhere near each other.

NAMED STARS
There are about six thousand stars visible to the naked eye in the sky. (I wonder if this is going to mean I get some hits if someone googles “naked”? Hmmm … naked naked naked naked …) Less than two hundred stars have individual names, primarily because remembering six thousand names is a little problematic. Still, the brightest stars all largely have names, and the commonly accepted names are largely from the Arabic. (I am not sure why Greeks named constellations and Arabs named stars. Perhaps Greek navigators didn’t need to be as precise navigating in the Mediterranean as Arabic travelers needed to be in the Indian Sea and aiming for small oases in big deserts.)
When I post star maps, I’ll post the names of all identified stars. If I miss any, I’ll try and fix that. This brings up an interesting point. For some years, there have been companies that allow you to “name” a star for a person. This is official – as far as that company is concerned, but nobody else knows about it. Have something cheaper! If you want to name a star, pick a star that has no name associated with it and send it to me (one per person, please), and I’ll mark it one the Messier Pro maps.

TIME:
When I refer to how the sky will appear on a certain night, unless I specifically refer to a certain time, I will be speaking of a time an hour after twilight has ended. This will generally be about two hours after sunset, and it will change over the course of the year. This “observing time” will be marked on the post, although any descriptions I give will be good for some time before and after “observing time” (unless I refer to something close to the western horizon).

Observing Staellites (Blog # -1)

2009-06-15T12:02:00.004-05:00

This is a long one, but don’t worry – you don’t have to read all of it!

Welcome to another somewhat introductory posting, (this is why the posts are still in negative numbers), but one that can hopefully enhance your stargazing straightaway. One of the websites that I have listed among my links is to a site called “Heavens Above”. I’m going to go into more depth on some of the benefits of this site, because it can provide location-specific star maps, and because of its satellite observing tools.

The space around the Earth has become pretty crowded in the fifty-plus years in human-made satellites have orbited the planet. It is a rare clear night on which even a casual observer does not notice an unblinking point of light tracing it way quickly across the sky. Satellites do not give off their own light, but can only be seen due to reflecting the Sun’s light. Given the small size of most satellites, this explains why even those in low orbits (about 600 km, or 360 miles, above the surface of the Earth) are faint when we see them. However, some satellites such as the Hubble Telescope and especially the International Space Station (ISS) can appear to be as bright as the brightest planets because they are in the lowest orbit (so rockets and shuttles from Earth can reach them economically) and both have large solar panels to provide their power, serving also as tremendous mirrors. These satellites can appear brighter than the brightest star, and even brighter than the brightest planet.

As it turns out, summer is an excellent time for observing satellites, even beyond the observation that for many people summer is a much more comfortable time to be outside. The reason for this has to do with the way that satellites are seen. In the diagrams shown, the Earth is drawn as a circle, and the orbit of a satellite orbiting the Earth is shown as a slightly larger circle. (Okay, this assumes a completely polar orbit – an orbit that takes satellites over the poles – but that isn’t too bad of an assumption and it exaggerates the size of a low-Earth-orbit satellite’s orbit. If the radius of the Earth is ten units, then the radius of the Hubble of the ISS is eleven units.) Since satellites are only seen from reflected sunlight, a satellite is only visible when it can see the Sun, but we (on the ground) can’t.

In the summer, as in the diagram on the right, we have short nights because the North Pole is tilted towards the Sun, which also allows much more of a satellite’s path to be visible. The thicker curve demonstrates the arc of the satellite’s orbit during which it is visible from our observing location. (The orange lines represent sunlight. The Sun is far enough away from the Earth that the Sun should best be thought of as a direction, not a point.)

In the winter, when the North Pole is tilted away from the Sun (this is not the Earth wobbling, it is tilted, rotating at an angle to its orbit) we have longer nights, and satellites are visible for less of their time above our horizon. Again, these diagrams are exaggerations, but the differences between the two seasons are still distinct.

To use the tools on Heavens Above, I set up a generic account for this blog, with a number of locations already specified. Once you are at Heavens Above, look under the “Configuration” heading for “Registered User Login” or “Create New Account”. (If the Heavens Above site has one problem, it is the sheer density of options available as a big, long column on the left.) Let’s start at the top under “Configuration”: while you could start by making your own account through “from database”, let’s start by looking at the Messier Pro account. Please click “Registered user login”. The login name I’ve set up for this is “Messier Pro” (yes, there is a space in the middle), and the password is “Hi Harry” (there is a space, and case does not matter). Now you will go to the home page for this account. (The default position for the observing location is Winona, Minnesota; if you don’t live there, click on the first active link under “Configuration” and change your location. I’m starting with Winona and Elbow Lake Minnesota; Green Bay, Wisconsin; Stephenson, Michigan; Philadelphia, Pennsylvania; Chattanooga, Tennessee; Knoxville, Tennessee; and Orlando Florida. If you aren’t in one of these places, feel free to add you own location to this list. (Sure, you could always just start your own account, but then we wouldn’t be “hanging out” together on line.)

There are many options you have from this point; I am just going to describe two now. If you scroll down past “Configuration”, and “Satellites” to “Astronomy”, a few lines down is the option “Whole sky chart”. If you click on this you will be taken to an image of the sky as seen from your location, right now. You can change the entries below the chart to adjust for any time and date, a handy feature.

You can also use this website to find times when bright satellites will be visible. Under “satellites” (no surprise), you can find times to see bright satellites including the Hubble Telescope and the International Space Station, as well as fainter satellites (including the toolbag that was dropped from the ISS some time ago), as well as finding all satellites brighter than a certain limit (the smaller the magnitude the brighter the object – I’ll explain this in my next post). To find a certain satellite, click on the link of your choice. This takes you to a table of visible passes. You can then click on the date to get more details, as well as a map of the path across the sky.

Suppose that you see a satellite, and want to identify it. Well, if I saw a satellite last night and thought to take note of the time and the path, I could click on the “Daily predictions for all satellites …” of my choice, click on “Previous PM” at the top, and work through the satellites of the last night to identify the one that I saw.

As an example, here are the next bright (brighter than any stars out at the time) passes for the International Space Station for each of the locations on the list:

Starting in the Upper Midwest:

Winona, Minnesota:
On Saturday, June 20th, the ISS will appear just over the southwestern horizon at 4:59 AM, stay relatively low to the horizon crossing into the southern sky, then the eastern sky through Capricornus, Aquarius, Pisces, and Cetus, to set in the constellation of Taurus.

Elbow Lake, Minnesota
Not surprisingly, the timing in this list is the same as the Winona pass, although these two towns are far enough apart (Minnesota is a tall state) that Elbow Lake can’t see several of the Winona passes as the path of the satellite over the next week or so will south of Winona more often than north. The ISS will appear at 4:59 AM in the south and hug the horizon to set just north of east. I wouldn’t suggest dragging the family out of bed on a Saturday morning to show them this.

Green Bay, Wisconsin
Green Bay is far enough away from Minnesota to see totally different passes. The ISS will get to about as bright as the brightest stars on these passes, the brighter starting at 3:50 AM on Sunday, June 21st. Like Winona and Elbow Lake, the orbit of the ISS when it passes over Wisconsin will result in the satellite appearing in the south and hugging the horizon to set in the east. At its best the ISS will not be more than 14 degrees above the horizon (overhead is 90 degrees). Sleep in.

Stephenson, Michigan
This is a really bad week to try and see the ISS from the UP of Michigan. The best view comes at 3:33 AM on Wednesday, June 24th. Not a lot to get out of bed for, but the ISS will pass close to Venus and Mars in the morning sky.

In the East:

Philadelphia, Pennsylvania
Again, more morning passes, although if you do have the will to get up for 4:50 in the morning, the ISS will be the brightest point in the sky, it will go almost directly overhead from the southwest to the northeast, it will be visible for nearly eight minutes, and it is a good way to identify the Northern Cross and Cassiopeia.

In the Southeast:

Chattanooga, Tennessee:
As in Winona, all of the bright passes of the ISS will be in the predawn morning. Sorry. However, if you get up on the morning of Sunday, June 21st, at 4:50 in the morning, the ISS will appear close to directly overhead, pass through Pegasus, Andromeda, and Perseus to set in the northeast three minutes later. Yes, this is early in the morning, but it might be the best opportunity on this list.

Knoxville, Tennessee
Still morning passes as we move back to the south, but if you can pull yourself out of bed at 5:33 AM on Friday (June 19th) morning, you’ll have a great view of the ISS covering pretty much the whole sky, appearing in the southwest and setting in the northeast. The pass lasts for about five and a half minutes and gets 67 degrees above the horizon. (The pass of Sunday, June 21st starts at 4:50 with the ISS appearing close to overhead and setting in the northeast.)

Orlando, Florida
It seems that all of the US just gets morning views for the next week, but if you are up at 5:09 on Thursday (June 18th), then you can see the ISS appear high in the south southwest (very close to the planet Jupiter, the only really bright thing in the southern sky) and travel to the northeast.

NEXT POST: Where to find the planets right now!

A User-Friendly Guide to the Universe (Blog # -2)

2009-06-11T17:50:00.000-05:00

Welcome to “The Messier Pro”, a blog about the universe as seen from your backyard. First things first though, what the heck does the name mean? It might seem like a very long way to go to make a little play on words concerning my wife’s blog, but at least the name was free, and I get at least one post out of trying to explain myself! That’s a victory … isn’t it? Let me explain the long way …

When I was about seven, I got the first astronomy book I can remember, and I began learning my way around the night sky. In seventh grade, I got a telescope with a lens that was actually smaller than the human eye. (Felt a little silly about that when I worked that out a few years later.) I spent two years working with that, then I moved on to a “department store telescope” which turned out to be a cardboard tube with a single lens at the end. I worked with this for four years, and then got a Schmidt-Cassegrain telescope with a mirror eight inches across for my high-school graduation. Some people got cars; I’ve covered much more distance with my ‘scope, and it’s lasted for more than twenty years. I hope this establishes my bona fides as someone with a little observing experience, and someone who got here the hard way. You don’t have to do that, and I can help.

The blog is named after Charles Messier, an astronomer who lived in eighteenth-century France. Astronomy even a hundred years ago was a lot different than it is now. Consider that even the basic about how stars work wasn’t even begun to be understood until the 1930’s. An astronomer in the 1700’s spent much of his/her (there was some “her”) time mapping the skies and looking for comets. Actually, this was much of the goal; if you discovered a comet, it was named for you, and whoever died with the most comets won. How did one go about, oh, eating, during this time, you ask? (No, really, surely somebody asked that? Anybody?) Ah well, here's the answer: One would find a suitably rich person and ask, “Pardon me, but if you pay for me to have an observatory and look for comets so I can discover them, I’ll tell everyone you gave me dough.” Surprisingly, this worked. It was something on the order of Michael Jordan’s endorsements, with less of a requirement to make public appearances in one’s underwear.

A comet, when it is first discovered, appears as a small fuzzy blob of light. Messier made a list of objects in the sky that appeared as comets (small, fuzzy, indistinct) and yet did not move from night to night, so they did not count as comets. To Messier’s mind, this was a garbage list, stuff to avoid, but we know recognize these as clusters of stars, great glowing clouds of gas, and whole .galaxies. Since I have been paid at various times to show these objects to people, I can claim to be a “Messier Pro”. Too cheesy? Maybe. Let’s move on quickly. (I will also be using items off of another list of object called the “Caldwell List”, made more recently by P Caldwell-Moore for the magazine Sky & Telescope in 1995. I will, when all is finished, try to compile a “Leckenby List” of objects that new observers can find, even when conditions aren’t perfect.

Actually, my first idea had been to write a blog focusing on the night sky as seen from the upper Midwest, but I’ve also gotten interest from a couple of people outside the area, so I thought that I would aim a little more widely. Why write a blog to begin with? Aren’t there many, many astronomy websites out there, many of them listed in the box to right? Why do you need MY electrons spinning out there on the internet? There are many astronomy sites out there now, but I have not found one that combines two assumptions that I will now lay out for you. I wanted to start a site that was accessible to someone who might not have any background in astronomy. There are many of these sites out there too, but I also wanted to combine this with an idea that not everyone lives in laces that have dark skies. My basic assumption is that my typical reader is in the ‘burbs. (If you are lucky enough to live with dark skies, my site will still help you; if you live downtown, it’ll be hard to see anything. Make friends with someone with a sky.) Sure there are also places that will make the sky available to you at times (I do it at my school at least monthly), but this is *your* universe – shouldn’t you get to use whenever *you* want? I think so. This will be aimed so that someone who has not been doing this for thirty-five years will not feel left out in the dark. (Rim shot.)

Many blogs will be tied to something going on in the sky at that time. Over the next couple of months, Saturn, Jupiter, Uranus, Neptune, the Moon, meteors and more will each have Messier Pro entries. My next entry will be about observing satellites, and why it is easier to see satellites in the summer. Many of my blogs will be about constellations; I will work my way through the sky, describing each of the constellations that can be easily observed from the mainland United States, and I will describe the constellations in three “layers”.

The first level of coverage will discuss the constellation as it can be seen with the eye. Hey, even if that’s all you got to work with, there is still a lot that can be gained by looking out at the sky with just your eyes – it’s what we had until 1609. The next level of coverage will discuss what can be seen with binoculars. Now, you won’t need to have huge or really spiffy binoculars (but if you have hem, don’t throw them away!); even small binoculars can greatly expand the universe available to you. The last level will be the small telescope. Did you get a telescope for your birthday or from some long distant holiday that’s just sitting in a closet gathering dust? Did you try to use it, only to get lost as some astronomy book/site seems to assume that you navigate the stars like Galileo, or that you can observe from a mountaintop in a National Park? I’m here for you!

NEXT BLOG: Observing Satellites, and I try to post more images!