Image generated with Starry Night Pro 6.
Draco, like all reptiles, is a bit on the dim side. Most of its constituent stars are in the 3 to 4.5 Magnitude range, making it an easy target in dark skies but a bit of a hunt near larger cities. If you’ve never looked for it before, it rivals Ursa Minor (the Little Dipper) in terms of “meh” apparent brightness in the sky (so it is far less pronounced than the Big Dipper or Cassiopeia, the two most prominent Constellations in this part of the sky).
Your best bet for identifying the stars in Draco may be to start right at the head and work your way down (and around, then over, then up, then way over the other way). One of my recent discoveries is that the head of Draco is, itself, a noted asterism (or noteworthy arrangement of stars that are not of the proper 88 Constellations) referred to as “The Lozenge” (“1″ in the image above). I had been subconsciously thinking of Monty Python references to throw into this article and realized that saying “The Lozenge” several in a low John Cleese voice a la “The Larch” just about does it. The head of Draco is made from the brightest stars in the Constellation and does make for a reasonably easy target, as it sits between the two bright stars of the Little Dipper’s bowl (“2″ In the image at right) and Vega (“3″), the ridiculously bright star making its triumphant return to Spring skies (if you’re at Darling Hill near sunset, you will see Vega as one of the first stars to appear above the Eastern Horizon well before it gets really dark). For those of you familiar with the Keystone (another famed asterism) that makes up the torso of Hercules (“4″ in the image above), simply drive your eyes to the left-ish during the early night.
The historical origins of Draco as a lizard of any kind are localized to the Mediterranean, and these origins go back far enough that Draco is one of the Almagest’s Original 48. The Greeks, and so the Romans, saw Draco as a Dragon (or, at least, lizard) of generally ill repute. Draco was seen by the Greeks as a guard of Hesperides’ golden apples and/or a guard (or target, depending on how you read the sentence) of Jason’s mythical golden fleece. The Romans saw Draco as the remains of the dragon killed by their goddess Minerva. It is perhaps fitting that, if you imagine Ursa Minor (the Little Dipper) as an ax on a questionably straight handle, then Draco is precariously on the celestial chopping block preparing to be cleft in twain.
The body of Draco is a healthy mix of single and double stars. In the boring single star category are Giausar, Thuban, and Nodus I. The double star list includes Edasich, Aldhibain, Altais, Rastaban (“eh mahn!”), Eltanin, and Grumium.
Thuban is one star in Draco to spend a bit of time on. In fact, it’s one to spend several thousand years on. As late as 2700 B.C.E., Thuban held the place of Polaris as our North Star. The Earth may seem reasonably unchanging with respect to the seemingly unchanging arrangement of stars of our 100-year-ish lifetimes, but on the geological or cosmological timescales our Earth is as dynamic and fast-moving as that famed clay dreidel. The 26,000-year cycle we know as the precession of the equinoxes (shown above) is one of those processes that requires nearly the entire history of what we know as civilization to mark significant timespans for, but it is reported in several places that Thuban was of significance to the Egyptians in their building of the pyramids over 5 millennia ago (I would be happy to report that Thuban was the North Star that the main shaft of the great pyramid of Cheops was aligned to, but I’ve found conflicting reports online from otherwise reputable locations, so will simply report that the Egyptians very likely knew that this star appeared to move far less over the course of the night than any other and, therefore, held it with great regard).
For those observing at Darling Hill or anywhere south of Syracuse, Draco is a tough reptile to sustain one’s astronomical appetite on. At least two comets are currently passing through Draco at the moment. One, LINEAR (C/2011 F1), is just off the Spindle Galaxy M102 (we’ll come back to that) and, at 3 a.u. and closing, may improve beyond its apparent magnitude of 12.5. Draco also hosts Garradd (C/2008 P1) far beyond its tail star. At an apparent magnitude of 21.30, you have absolutely NO chance of seeing this comet from Darling Hill.
Draco is regrettably light on deep sky objects as well. The local color (at about 3400 light year) is provided by NGC 6543, known as the Cat’s Eye Nebula (above). This is regarded as one of the most structurally complex nebulae in the Night Sky, although this complexity is only revealed through astrophotographic studies. NGC 5866 (below), also known as the Spindle Galaxy (which is very likely Messier 102, although some debate exists), is one of the great photographic sights in astronomy to my eyes. This edge-on galaxy view produces amazing density of material and spindly, fibrous clouds of dust and stars along the plane of the galaxy and a bright glow of stars all around this dense, dark line.
Now, the long curving body of Draco and its positions near the North Star does afford it one benefit in the Northern Horizon. Satellites! There are many bright (brighter than magnitude 4.0) satellites that follow paths over the Earth’s poles, meaning those Constellations near the North and South poles are constantly getting pierced by manmade weather, communications, and “other” satellites. Simply letting my copy of Starry Night Pro go at high-speed with Draco at the center reveals over a dozen of these satellites over the course of just a few hours.
Image generated with Starry Night Pro 6.
Much can be said about the old hunter Orion. To Central New York observers, it had (until very recently) been the case that Orion made his way across the Night Sky during the coldest and least hospitable (to most nighttime observers) months of the year. Conditions would keep observers in hiding from him (some of the best CNY observers I know would risk surgical strikes on the Orion Nebula with their fastest to set-up and tear-down equipment). The abbreviated winter of 2011/2012 and reasonably early start of the SAS observing season have provided us with excellent opportunities in the past few months to make Orion The Hunter now the hunted. The mid-April observing session will be the last “official” opportunity to observe Orion before he disappears behind the Western horizon until the most nocturnal of us can next see him in our Eastern sky before sunrise in late August. I then take this opportunity to discuss Orion, one many CNY/SAS members may know the best by sight but may know the least by observing attention.
One of the topics covered in the 2011 SAS lecturing series was how we observe. Not the discussion of optics or the physics of planetary motion along the ecliptic, but the visual and mental mechanisms we use to translate the photonic triggers in our retina into mental pictures of celestial objects. Orion was the astronomical example I used to describe Pareidolia, how we impose a kind of order on things we see despite that order not being present in the actual collection. When you look at a cloud, you may see a face, an animal, or something your mind triggers as being something it clearly is not. I often placed the infamous “Face On Mars” next to the Constellation Orion to show clearly how we see what we think we see despite all reasonable evidence to the contrary (or the two can be mangled together, as shown below). The clouds may look like an animal, the “Face On Mars” looks unmistakably like a shadowed face, and Orion, as it happens, has looked like a human figure to virtually all peoples for as long as we have record of Constellations, the same way Scorpius has appeared as a scorpion to every civilization for which this little monster was part of the local biosphere.
Pareidolia is not just for cognitive neuroscience! One of the keys to learning the sky I discussed last year was to let your mind wander while staring at the sky and see if certain things jump out at you. The constellations are, for the most part, made up of the most reasonably bright star groupings, but if you see any type of geometry that makes some part of the sky easy to identify, run with it. This same philosophy may be responsible for the rise of the asterism, or “non-Constellation star grouping,” as the distillation of mythological complexity into more practical tools for everyday living. For instance, I suspect everyone reading this can find the asterism known as the Big Dipper, but how many know all of the stars of its proper Constellation Ursa Major? Our southern tree line and Cortland obscure some of the grandeur of Sagittarius, which means we at the hill identify the location of its core (and several galactic highlights) by the easy-to-see “teapot.” The body of Orion is a similar case of reduction-to-apparent, as the four stars marking his corners (clockwise from upper left)…
Betelgeuse (pronounced “Betelgeuse Betelgeuse Betelgeuse!” – marking his right shoulder; a red supergiant of very orange-ish color even without binoculars)
Bellatrix – the left shoulder (so you now know the Constellation is facing us as originally defined) – a blue giant known also known as the “Amazon Star”
Rigel – the left foot; a blue supergiant and the star system within which the aliens that make the Rigel Quick Finder reside
Saiph – the right foot; a star dim in the visible but markedly brighter in the ultraviolet. Saiph and Rigel are about the same distance away (Saiph 50 light years closer at 724 light years, a point to consider as you observe them both)
… and the three stars marking his belt (from left)…
Alnitak – A triple-star system 800 light years away with a blue supergiant as its anchor star
Alnilam – the farthest star of the belt at 1359 light years, this young blue supergiant burns as brightly as the other two, making the belt appear equally bright “al across”
Mintaka – 900 light years away, this is an eclipsing binary star system, meaning one star passes between us and the main star in its orbit (about every 5.7 days)
… are obvious to all, while the head and club stars require a longer look to identify.
Sticking to Naked Eye observing for a moment, Orion is not only famous for its historical significance and apparent brightness. Orion is ideally oriented to serve as an order of alignment for several nearby Constellations and is surrounded by enough bright stars and significant Constellations that curiosity alone should have you familiar with this part of the sky in very short order. As an April focus, it is of benefit that all of the Constellations we’ll focus on either hit the horizon at the same time as Orion or they rest above him.
I’ve color-coded the significant stars marking notable Constellations in the image below. If you’re standing outside on any clear night, the marked stars should all be quite obvious (we’re talking a hands’ width or two at arm’s length). From right and working our way counterclockwise…
(RED) Following the belt stars to the right will lead you to the orange-ish star Aldebaran, marking the eye of Taurus the Bull. This is a dense part of the sky, as Aldebaran marks both the head of the Bull and also marks the brightest star in the Hyades star cluster (a gravitationally-bound open cluster 150 light years away composed of over 100 stars). Just to the right of this cluster is the “Tiny Dipper” known as the Pleiades (Messier 45), another dense star cluster worth observing at all magnifications. Both of these clusters are simultaneously easier and harder to find at present, as Venus (“1″) is resting just above them, providing an easy way to find both clusters but plenty of reflected light to dull the brilliance of the two open clusters.
(ORANGE) Auriga, featuring Capella (the third brightest star in the Night Sky), is an oddly-shaped hexagon featuring a small triangle at one corner. Auriga, like Ursa Minor in last month’s discussion, is made easy to find by the fact that the five marked stars are in an otherwise nondescript part of the sky (relatively dim generally, but brighter than anything in the vicinity). Venus will dull Hassaleh (Auriga’s closest star to Venus and the two open clusters below it) but Elnath and Capella will be easy finds.
(YELLOW) Castor and Pollux, the twins of Gemini, are literally standing on Orion’s club. Making an arrow from Mintaka (the right-most star of the belt) and Betelgeuse will lead you to Alhena (Pollux’s left foot), after which a slow curve in a horseshoe shape will give you the remaining stars.
(GREEN) Canis Minor is two stars (which is boring), but is significant for containing Procyon, the 7th brightest star in the Night Sky (which means it will be an EASY find). But don’t confuse it with Sirius, which is the big shimmering star in…
(BLUE) Canis Major is the larger of Orion’s two dogs and contains Sirius (“The Dog Star”), a star so bright (magnitude −1.46) and so close (8.6 light years) that it appears not as a star but as a shimmering light. Some would say an airplane, others would say a hovering UFO. Part of my duties as president involve intermittently explaining that it is not the latter.
And, with respect, Monoceros is an old Constellation but not a particularly brilliant one. Having Canis Minor and Canis Major identified will make your identification of Monoceros quite straightforward.
We now turn to the other “stellar” objects in Orion, composed of three Messiers and one famous IC. M78 is a diffuse nebula almost one belt width above and perpendicular to Alnitak. You will know it when you see it. M43 and M42 (marked as “4″ in the image below), on the other hand, are so bright and close that you can see their nebulosity in dark skies without aid of any optics.
M42 – The Orion Nebula is, in the right dark conditions, a Naked Eye sight in itself. For those of us between cities, even low-power binoculars bring out the wispy edges and cloudy core of this nebula. For higher-power observers, the resolving of Trapezium at M42′s core serves as one of your best tests of astronomy binoculars (I consider the identification of four stars as THE proper test of a pair of 25×100′s. Ideal conditions and a larger aperture will get you six stars total). You could spend all night just exploring the edges and depths of this nebula. You can take a look back at the Astro Bob article in the April 2012 edition of the Astronomical Chronicle (From My Driveway To Orion, Nature Works Wonders) for a more detailed discussion of this part of Orion.
M43 – de Mairan’s Nebula is, truth be told, a lucky designation. M43 is, in fact, part of the M42 nebula that is itself a small part of the Orion Molecular Cloud Complex (not THAT’S a label). M43 owes its differentiation to a dark lane of dust that breaks M43 and M42, just as the lane of dust in our own Milky Way we know as the “Great Rift” splits what would otherwise be one continuous band of distant stars the same way a large rock in a stream causes the water to split in two and recombine on the other side.
Finally (and the one you’ll work for), IC 434, the Horsehead Nebula, lies just to the lower-left of Alnitak (1). The Horsehead is itself a dark nebula, a region absorbing light to make it pronounced by its difference from the lighter regions around it. To put the whole area into perspective, The Horsehead is itself STILL within the Orion Molecular Cloud Complex. The sheath of Orion’s Sword and nearly the entire belt is contained in this Complex, like dust being rattled off with each blow from Orion’s club.
I close by taking a look at the perilously ignored club attempting to tear into Taurus. At present, asteroids surround Orion’s Club like pieces of debris flying off after a hard impact. All are in the vicinity of 12th magnitude (so require a decent-sized mirror), and all are also moving at a sufficiently fast clip that their paths can be seen to change over several observing sessions (if, by miracle, enough clear days in a row can be had to make these measurements). I have highlighted the five prominent ones in the image below.
Is it an oddity to have Orion so full of asteroids? Certainly not! Orion is placed near the ecliptic, the apparent path of the planets in their motion around the Sun. Orion’s club just barely grazes the ecliptic at the Gemini/Taurus border, two of the 12 Constellations of the Zodiac, the collection of Constellations that themselves mark the ecliptic. As nearly all of the objects in the Solar System lie near or within the disc of the Solar System, you expect to find all manner of smaller objects in the vicinity of the Zodiacal Constellations. In effect, Orion’s club is kicking up different dust all year long as the asteroids orbit the Sun. You only have a few more weeks to watch the action happen before Orion’s return in the very early early morning of the very late summer.
- Happy Hunting, Damian
As first appeared in the January/February/March 2012 edition (yeah, I know) of the Syracuse Astronomical Society newsletter The Astronomical Chronicle (PDF) and, I am proud to say, soon to be included in an edition of the Mohawk Valley Astronomical Society (MVAS) newsletter, Telescopic Topics.
Image generated with Starry Night Pro 6.
[Author's Note: A tradition owing to Dr. Stu Forster during his many years as President and Editor, the Syracuse Astronomical Society (www.syracuse-astro.org) features (at least) one Constellation in each edition of its near-monthly newsletter, the Astronomical Chronicle.]
The Constellation discussion for this year is going to take a bit of a turn.
As part of the 2011 Syracuse Astronomical Society (SAS) lectures presented at Liverpool Public Library and Beaver Lake Nature Center, I spent a few minutes covering (briefly) how to navigate the Night Sky. By way of introduction, I described how one of my graduate advisors, Dr. Bruce Hudson, began scribbling furiously a long string of quantum mechanical equations about something-or-other that devoured the lion’s share of a whiteboard. Upon mentioning that I had no idea how he kept such information at the ready in his noggin, he replied “Try doing it 50 years.”
It is, in my humble opinion, useless to present the 88 Constellations to a general, new-to-observing audience in an hour and expect anyone to remember information that I, as el presidente, am still trying to digest after several years (a problem made all the more infuriating by the fact that this information hasn’t changed in several millennia). The problem that I and others at this latitude have is that the vast majority of the Night Sky changes throughout the year and, given that weather conditions often result in short spells of clear sky and long patches of overcast conditions, there is often little opportunity for “mental reinforcement” to help commit the lesser (well, at least smaller or dimmer) Constellations to memory.
The solution I discussed in the lectures was to play the “observability odds” and focus on learning those Constellations that you can, given clear skies, see all year long from Central New York (CNY). This group of Constellations are defined as “circumpolar” and, by their location about the axis of rotation of the Earth, never dip below the West/Northwest Horizon (or, at least, they do not entirely disappear over the course of a long evening of observing unless you’re surrounded by considerable foliage).
The set of images at the end of this article will show you how to kill six birds with one long, clear turn of the stone we call Earth. The small family of six Constellations I’ve included in this discussion are (1) Ursa Major (although, here, I’m only including the Big Dipper asterism for ease of identification. This is obviously a better target for new observers), (2) Draco the Dragon (a long and winding Constellation that is curled around the Little Dipper), (3) Cepheus, the late-late-late King of Ethiopia (as much as I dislike the use of simple geometric objects to identify groups of stars (because, well, they’re all points on imaginary polygons), the odd pentagon does stand out at night), (4) Cassiopeia (Jonathan Winters’ Big “W” and, thanks to Earth’s rotation axis, also sometimes a “3,” or an “M,” or an “E,” but obvious upon first being pointed out), and (5) Camelopardalis the giraffe (one of the last Constellations you might otherwise learn. Also one of the last Northern Constellations marked as such, in this case in 1612 by Petrus Plancius. You might even have a little trouble picking this one out. The Greeks (for instance, and in their infinite wisdom (I note with a 100% Greek heritage)) did not even bother to identify anything in this part of the sky as being of significance given how relatively dim the stars are). This list leaves number six, Ursa Minor, which I denote in the images as “0″ as your celestial clock face base of operations.
Ursa Minor, or the Little Dipper (below, shown at its approximate orientation at 10:00 p.m. on March 23rd), is a nondescript Constellation that requires a bit of searching to find in the Night Sky. Polaris, its last handle star (2.0 mag.), is made easier to find by the fact that it is in a very dark, very nondescript piece of sky (it is identifiable simply by being where it is). Its cup-edge stars Pherkad (3.0 mag.) and Kochab (2.1 mag.) are a bit brighter and also in a dull region of the sky. The four remaining stars are the ones that become more visible as you mark their location with your scanning eyes. These four are made a bit more difficult to find from Darling Hill Observatory (home of the SAS) because of the bright light bulb directly at our Northern Horizon that is downtown Syracuse.
A possible trick to finding Polaris for the new-at-observing is to use the two most prominent Constellations in the North, Ursa Major (again, using the Big Dipper asterism here) and Cassiopeia. Finding the bowl of the Big Dipper and imagining a clock face, find Cassiopeia at nearly 7 o’clock to the edge-most bowl stars, then aim for the location where you’d expect those hands to be riveted (as shown below). Again, you’ll find a single bright-ish (“eh”) star at this location.
Having sufficiently talked down the significance of Polaris as a celestial observable, this otherwise nondescript star has something other nondescript stars have. To quote “Glorious John” Dryden:
Rude as their ships were navigated then;
No useful compass, no meridian known;
Coasting they kept the land within their ken;
And knew no North but when the Pole star shown.
Or, as William Tyler Olcott sums more quickly in his book “Star Lore,” Polaris is “the most practically useful star in the heavens.” Modern civilizations know Polaris as the star around which the Earth appears to spin, making it the most stably-placed object in the Night Sky over any reasonable span of human existence (a qualification I use in this article to avoid a discussion of the fascinating but “not relevant to learning the Night Sky right now” Precession of the Equinoxes).
The apparent constancy of all of the star positions (and Constellations) in the Night Sky relative to one another is, of course, due to stellar parallax, the celestial equivalent of the more familiar terrestrial parallax. If you’ve ever been the passenger on a long drive, you’ve borne witness to the trees along the road moving at a tremendous clip while the distant trees slide far more slowly through your field of view (that is, stay in your field of view while the trees along the road fall far behind you over the same amount of time). Polaris provides an ideal example of this same phenomenon on a celestial scale by its apparent immovability in the Night Sky despite the best efforts of Earth as it reaches nearly 300,000,000 kilometers of physical separation from its starting point every six months. The two images below demonstrate the phenomenon…
Your Green Laser Along Earth’s Rotation Axis (Pointing UP From The North Pole), One Beam Every Three Months, Separated By (At Best) 2 Astronomical Units (a.u.), Looking At A “Close Object” With A Large Apparent Motion Against The “Background”
Your Green Laser Along Earth’s Rotation Axis (Pointing UP From The North Pole), One Beam Every Three Months, Marking A Position 431 Light Years Away (Looking At A “Distant Object”) And A Small Apparent Motion Against The “Background” (All NOT To Scale)
At above-left you see a small slightly-sideways model of Earth’s motion around the Sun (at points being marked about every three months), with the left-most and right-most positions separated by two astronomical units, the astronomical unit being the mean distance between the Sun and Earth (bearing in mind Kepler‘s Elliptical description of our orbits), a value of about 150 million kilometers. To objects in our own Solar System or even a few nearby stars, this large change in position is enough to clearly see those objects that are nearby move more than the “background” of more distant objects (you could do this at home with a decent scope and excellent note-taking skills, possibly reproducing the 1838 work of Friedrich Bessel in his measurement of the parallax of 61 Cygni). In our case, the more distant objects are the stars far from our vantage point (think of “stars” as “trees” and the same driving analogy works, although now you’re driving around a circular track and paying your passenger to always look North). Polaris, as measured by the Hipparcos satellite (using parallax to exacting detail), determined that Polaris is 431 light years away, a distance of 27.5 million a.u.! And this is a CLOSE star considering the 100,000 light year diameter of the Milky Way. At this distance, if the four green laser pointer beams were a meter long, their separation in Earth’s orbit would be a small enough measuring distance to map out the contents of a single-celled organism in exacting detail. My ability to draw a proper parallax-like image to show this is limited by the pixels on my screen being gigantic compared to the apparent change in position in this crude image (so the above image is decidedly NOT to scale).
All of this discussion above is basically to convince you that, when you look up in the Night Sky, Polaris will effectively NOT move to the best of your ability to observe it, making it a best starting point for your Constellation memorization adventure.
Well, Polaris will NOT move provided you always observe from the same latitude on the Earth’s Surface. The last piece of the puzzle to put ourselves into proper perspective comes from a zoom-in of our Earth, shown below. You’ll see that our North Pole, appropriately placed at 90o North Latitude, is aligned nearly exactly with Polaris (again, for our purposes, this approximation is fine). What does that mean? It means that, with the right low Horizon (or high hill), nearly ALL of the Northern Constellations are circumpolar at the North Pole! Think of the memorization mess! Alternatively, at the equator (0o), the Night Sky is, effectively, constantly in motion (this should make you truly appreciate the navigational and astronomical skills of the Polynesians in their spread across the South Pacific islands).
As you walk from the Equator to the North Pole, moving from 0o to 90o North Latitude, the North Star appears to get higher and higher in the Night Sky. By this, the angle of Polaris above the Horizon (its altitude) is equal to our latitude (so when you know one (say, by getting your latitude and longitude from google maps or the like), you know the other. This is one of the great “then explain this, dummy!” rhetorical smack-downs to members of the Flat Earth Society). In our case, Polaris is about 40o above our horizon. Personally, I think 40o North Latitude is a perfectly reasonable place to begin Constellation memorization. Not too many, not to few. And, as is the common theme we’ll explore this year, once you have a reliable base of celestial operations, learning the remaining Constellations becomes a significantly easier (but still Herculean) task.
The Counterclockwise Circumpolar Map
Your Northern Horizon from CNY will, clear skies permitting, ALWAYS look something like the following, with the Constellation closest to the N/NW Horizon labeled as follows (0 = Ursa Minor, the Little Dipper. * = Polaris, which appears to not move (to a coarse approximation)):
A. Big Dipper (1, technically, Ursa Major, but the Big Dipper is smaller and more obvious)
B. Draco (2, aim for the dragon’s head. If the Big Dipper is N/NE, an easy find)
C. Cepheus – 3, a crazy house standing upright, just right of a bright “E”
D. Cassiopeia – 4, the big “W,” at the horizon an “E” (or its canonical chair)
E. Camelopardalis (?!) – 5, the back-end of a giraffe(with Cassiopeia as a “Big W,” the giraffe is drinking from the tipped bowl of the Big Dipper).
NOTE: The Earth’s rotation makes 1-to-5 move counterclockwise! Fresh Constellations over your Eastern Horizon, stale ones disappear at your West.
Happy Hunting – Damian
Constellation Map generated with Starry Night Pro 6.
It is only fitting that, as we approach Summer and the unbelievable wealth of binocular and telescope objects that reside within the central region of the Milky Way, we spend at least one article on an otherwise mundane (to the amateur astronomer, anyway) Constellation. We endeavor this act of balance in the presentation of night sky viewing (and in the interest of accounting for all of the sky by the time these articles are done) by featuring Libra, The Scales.
The history of Libra in Western culture is one of science, religion, theft, imminent domain, here-say, and whatever existed as copyright in the Roman days (it is tough to make a Constellation associated with the Law interesting enough for prime time TV, as the only thing there is to murder is the presentation of any historical interpretation attributed to it). The reference to this collection of stars as a balance is reported to go as far back as the Sumerians (approximately 2000 B.C.), where this collection was known as “ZIBBA AN-NA”, or the “balance of heaven.” It is of particularly humorous irony this month that the Greeks were responsible for the disappearance of “the balance” from the night sky in favor of over-inflating the magnitude of the already important constellation Scorpius (for historical perspective, this article is being written as Greek economic infrastructure is falling apart faster than the Parthenon during the Siege of Athens in 1687 by Francesco Morosini, the Doge of Venice [as a good Greek, I shake my fist at the Gods in anger]).
The Romans saw fit to either return to the Sumerian tradition or simply declaw Scorpius, as Libra once again became a set of Scales. It is fate that the pinchers of an arthropod would be returned to the type of covering for reptiles. With the first publications of Libra-friendly star groupings and names upon the demotion of the now more diminutive Scorpius, one might even argue that the pen is mightier than the claws.
When not being visually accosted by rock n’ roll advertisements for lawyers behind cheap bookcase backdrops offering beaucoup bucks for your injury settlements, the legal profession often seems quite dull and arcane in its own right (sorry, Ray). Libra is equally subdued in its presentation, offering no Messier Objects within its official borders and no other really “interesting” things observable through binoculars or small telescopes. Perhaps the most interesting aspect about the constellation itself is its identification as the only inanimate object of the Zodiac, the ring of Constellations that encompass the ecliptic, or the apparent path of the Sun throughout the year.
That is not, however, to say that there isn’t anything worth its weight in hydrogen residing within the Libra boundaries. If we perform a considerable zooming in just above Zubeneschamali (phew! That translates to the “northern claw,” just as its counterpart Zubenelgenubi translates to the “southern claw.” These names would indicate that Arab astronomers opted to use both Greek and Roman sources despite the obvious conflict in the star groupings), we can see (with very good scopes) the star Gliese 581 (shown below), home of one of the most populated planetary systems yet discovered (although it is important to remember that this number is only of those planets we can detect, which means those with significant gravitational influence on their stellar anchor). This is marked “1” in the opening image. To date, there are four detected stars around Gliese 581 (note that the star name is always first, followed by a letter designation), including Gliese 581 b, a Neptune-sized object with a 5.4 day orbit, c, a rocky Earth-like planet within the Gliese 581 Habitable Zone 1.5 times wider and 5 times more dense than our own, d, a planet 1/2 as massive as Uranus and still within in the Habitable Zone, and e, a planet 1.6 times as massive as Earth and the smallest yet identified. the star Gliese 581 not only represents a feat of mathematical prowess on the part of Terran researchers, but is also of specific interest because of the number of planets within its Habitable Zone, the region within which conditions are believed to be similar to our own (specifically, liquid water on the surface). Some even refer to this as the “Goldilocks Zone,” where it’s not too cold and not too hot. One might say that this region is where a proper balance of hot and cold is reached…
Of all of the asterisms (groups of stars that are not designated as Constellations but that still have specific meaning. For instance, the Big Dipper is an asterism within the Constellation Ursa Major) that have jumped out at me during my binocular viewing adventures, the one marked by the “2″ is perhaps the one that most stood out to my eyes. It is one of the most perfect isosceles triangles in the nighttime sky and is reasonably clear around it such that only this shape stands out in low-power optics. When it’s out, I always look for this small golden nugget residing within the Zubeneschamali-side of the scales, tipping the balance towards the arrival of the Summer constellations Scorpius and Sagittarius, the pair that mark the inside of our own galaxy and where a disproportionate number of Messier riches abound.
|Image generated with Starry Night Pro 6, www.starrynight.com.|
The Constellations, for all of their mythological, mystical, and ceremonial significance throughout human history, are also the bases for much of the scientific discovery (the Zodiac was a calendar long before it was ever used to identify the other kind of dates, and the backdrop of the unchanging Heavens served as the guide against which the motions of the planets were first tracked) that fueled our understanding of the universe before Edwin Hubble first exposed its true vastness by identifying the “Andromeda Nebula” as, in fact, a galaxy far outside of the Milky Way. The constellations have also served in a far more pragmatic capacity throughout human history as seasonal sign posts, simply marking times and locations for those on land and sea. Perhaps the most famous example of this in American History is the use of the Big Dipper as the marker by freed slaves traveling North along the Underground Railroad. The song “Follow the Drinkin’ Gourd” is not simply a series of verses, but is instead a set of instructions, with the “Drinkin’ Gourd” being the Big Dipper, the most easily recognizable asterism in the Northern Hemisphere (amateur astronomer or not) and pointer (by drawing an arrow from Merak to Dubhe) to the North Star Polaris, itself the most famous star of the Little Dipper (also known as Ursa Minor), an otherwise somewhat unimpressive constellation (certainly not as prominent in the North as the Big Dipper or the Cassiopeia “W” and, therefore, not as useful a sign post).
The Little Dipper is not the most prominent constellation in the Night Sky, but it serves as an important terrestrial marker because it includes Polaris among its member stars. Just as the Big Dipper is a prominent asterism that directs you to the Little Dipper, the Summer constellation Scorpius (which has been recognized specifically as a scorpion by many cultures for several millennia) can draw you to a slightly less prominent constellation to its West that is a sign post to a far more impressive marker than Polaris.
Sagittarius is an astronomy instructor’s dream constellation, as it wraps up a number of interesting topics of discussion in one easy-to-find location. To begin, the Centaur, a half-human/half-horse hybrid, is the perfect bridge between the fantastical world of mythology in all of its seeming ridiculousness and, well, the shining example of what might even be ridiculously possible as scientists learn more about DNA and biological engineering (as of this past May, we now can make monkeys that glow in the dark. That’s right, in the dark).
Second, Sagittarius provides its viewer another shining example of the difference between a constellation and an asterism. A constellation is, simply, a specific grouping of stars that everyone has agreed are, in fact, assigned to that particular constellation. This circular definition was finally laid flat by the International Astronomical Union in its defining of Constellation Boundaries, solidifying star groupings that go as far back as antiquity and as far forward as 1763 (the exploration of the Southern Hemisphere was not limited to the land and the sea). An asterism is, simply, a convenient grouping of stars that are NOT one of the 88 Official Constellations, with some asterisms being only fragments of a full Constellation (such as the Big Dipper, the most famous asterism in the Constellation Ursa Major) and some asterisms composed of parts of multiple Constellations (such as the Summer Triangle, composed of the stars Deneb (Cygnus), Altair (Aquila), and Vega (Lyra). At our latitude (Syracuse and Tully), we cannot even see the entire Constellation of Sagittarius, but have an excellent view during the Summer of one of the most modern of conveniences in the form of a Tea Pot (see below). We may seem a little ridiculous pointing out the tea pot, short and stout, with its handle (on the left or to the West) and its spout (on the right or to the East) at Darling Hill on a dark night, but you will not forget this asterism after it jumps out at you the first time. An important thing to remember is that any grouping of stars in the sky that helps YOU find what you are looking for is as significant an asterism as one you might find in any book. If an otherwise unlabeled grouping jumps out at you that helps you find your place in the Night Sky, put those informal naming rights to good use.
|Image generated with Starry Night Pro 6, www.starrynight.com.|
Third, the billowing steam from the spout of this tea pot marks a most important location to all 100 billion or more stars in our galaxy. The small darkened oval in the picture above marks the exact location of the center of the Milky Way galaxy (the tiny, fuzzy spec at its middle), meaning we are looking into the most dense region of the galaxy when we set our gazes at this region. Unfortunately, the city lights from Cortland wash the density of the Milky Way band at our South when we observe in Tully, although the full band of the Milky Way is prominent above us during the Summer.
|Images from ircamera.as.arizona.edu.|
Fourth, because we are looking into the heart of the Milky Way when we see the spout of the tea pot (as the image at right tries to show), we are looking into the densest region of stars we can see from Earth. As a result, this tea pot marks the location of a variety of Messier Objects and fainter nebulae far more numerous than even the largest variety pack the other Celestial Seasonings (pardon the tea pun) has to offer. The Trifid Nebula (M20), Lagoon Nebula (M8), Sagittarius Cluster (M22), Omega Nebula (M17), Black Swan Nebula (M18), M25, M23, M55, M54, M70, M28, M21, and M75 all reside within the Sagittarius boundary, while M6, M7, M16, and a host of other deep sky objects surround its borders in neighboring Scorpius, Ophiuchus, and Serpens Cauda.
When we observe during the Summer, I often recommend to new visitors with binoculars to simply point to the South, aim for the tea pot, and slowly scan. If your binoculars or telescope are anywhere near focused, you are guaranteed to find something within your field of view.
Mildly thirsty just thinking about it,