Eagles

.....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

.....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!

.....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.

Names Out the Wazoo

.....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.

Lyre Solo (or Solo Lyre)

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

.....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 August Sky

.....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.