Some Light Science Reading. The Constellations: Pegasus

As first appeared in the September 2010 edition of the Syracuse Astronomical Society newsletter The Astronomical Chronicle (PDF).

Constellation Map generated with Starry Night Pro 6.

The Constellation this month is one light on interesting binocular and telescope objects but heavy in mythology and Naked Eye observing. To the Babylonians, the stars in this region also (or first) took on the shape of a horse known as MUL.ANSHE.KUR.RA. To the Greeks, sometimes a horse is not (just) a horse (of course, of course). The Greek mythology surrounding the winged horse Pegasus is, to say the least, involved and undecided. There are several pages discussing the mythology of Pegasus, which I refer you to in the interest of local brevity.

The torso of Pegasus is composed of a "Great Square" of stars that is very easy to see and is very often pointed out to visitors at this time of year at Darling Hill. This asterism (simply any grouping of stars that are not officially constellations) lies to the right (or south) of the Andromeda Galaxy (M31), one of the great views in the Autumn skies. As the scope is pointed in this direction anyway for a good block of time during Public Viewing sessions, the walk through some of the nearby Constellations (Cassiopeia, Perseus, Andromeda, Pegasus, Cepheus) reads like a Cliff Notes version of both Clash Of The Titans movies (unless John McMahon is running the presentation, in which case you're guaranteed a much better show). In the modern definition of the Constellations, the south-most (or upper left corner) star belongs instead to the Constellation Andromeda (but anyone staring at this part of the sky would be hard pressed to be struck more by the "Great Triangle" of Pegasus than the "Great Square" of Pegasus).

There are only two significant (and visually accessible) objects within Pegasus (the Constellation, that is) for the binocular and telescope viewer at Darling Hill. The first of these is the appropriately named Pegasus Cluster (M15), an ancient globular cluster clocked at 13.2 billion years of age. This cluster appears as a smaller version of M13 in Hercules, as captured by our own Stu Forster in the September 2008 Member Gallery and shown below. The second object is a far more difficult find, the very unique spiral galaxy NGC 7742 (below). The presence of a prominent ring in this galaxy (or, more specifically, the absence of pronounced spiraling from the center of the galaxy out to the edges) is a point of unexplained inquiry in modern astrophysics.

M15, photo taken by SAS member Stu Forster.
NGC 7742, image from the Hubble Heritage Team (AURA/STScI/NASA/ESA).

The most curious content on the wikipedia page for Pegasus involves the nontrivial amount of discussion about the reinterpretation of its connectivity by one H. A. Rey in, specifically, his book The Stars — A New Way To See Them. Rey's goal in this book is to redefine connectivity of some of the Constellations to make them a bit easier to see as the mythical beasts they are known for. For Pegasus (see below), Rey has eliminated any mention of Sirrah (or Alpheratz, as it's known within Andromeda), using the Great Square as a Great Triangle that marks the above-the-shoulder wings over the trapezoid torso (with the rest of the limbs along the southern edge of the Constellation). Upon inspection, his reinterpretation looked more to me like one of the drawings of The Man In The Yellow Hat who, along with Curious George, is perhaps the more famous of the illustrated characters created by H. A. Rey.

A new view of an old constellation, or The Batman In The Yellow Hat.

I'll admit I'm mildly ambivalent about the redefinition of Constellation connectivity. On the one hand, the Constellations are one of the oldest memes in human history among all societies (extant or extinct) and, to that end, connectivity has meaning as a way of marking out specific arrangements that have largely stood the test of time. The consistency of connectivity also provides a way to reduce the memorization fatigue that comes from having to see groups of stars in slightly different ways (clearly, one arrangement is easier to know and explain than several). This is of further significance when one uses Constellations as a specific guide to locating Messier (or other) objects. If I tell you that "M15 is on an almost straight line about 1/2 the distance of the two stars that make up the snout," you really have to trust that we're seeing the same horse!

On the other hand, there are many amateur astronomers who use Constellations largely as tools for finding smaller objects (with or without a knowledge of their history) and, as we are a species that excels at pattern recognition (how many flying faces and hippopotami can you see on a partly cloudy afternoon?), anything that makes life easier for you the observer (especially on cold nights when observing time is at a premium) should be added to your observing arsenal. H. A. Rey's interpretation of Pegasus connectivity might cloud just how pronounced the Great Square is (so you have to then present this Constellation with an addendum!), but it certainly does look more like a complete flying horse than the common artistic rendering of only the front half (clearly the side you'd want to have over you anyway given both choices).

Any way you look at it, it's still safe to assume that the winged horse must have been the most efficient way to travel in the ancient world. It certainly speeds up a good plot.

Clear skies, Damian

Some Light Science Reading. The Constellations: Pisces

As first appeared in the August 2010 edition of the Syracuse Astronomical Society newsletter The Astronomical Chronicle (PDF).

Constellation Map generated with Starry Night Pro 6.

Those who've ever been told that "there are more fish in the sea…" should be relieved that we only cast our visual nets to the heavens for stars and galaxies, as this most important of animals throughout history is only represented in the Northern Hemisphere by one pair of gilled swimmers tied at the tails.

The identification of one-half of this constellation as a fish (its other half had originally been a dove) dates back to at least Babylonian times, when a second great Western civilization prospered in the valley of the Tigris and Euphrates rivers to the West of Egypt, home of the first great Western civilization at the Nile Delta. The two civilizations from which most of the astrology (and mythology) that turned into early astronomy was established were founded by key water sources, providing the means for irrigation, transportation, and stable food supplies in the form of fishing, the three key needs of a society that allow for growth and the ability of the few to support the many (as James Burke has considered in Connections and The Day The Universe Changed, the ability of people to NOT need to provide subsistence level support for a society is what promotes scientific growth, cultural evolution, and whatever other types of activities most of us attend to everyday while some small fraction of the U.S. harvests or raises the food that the rest of us consume with hasty abandon). The Greeks eventually solidified the tied-fish representation of Pisces, representing Aphrodite and Eros, tied to one another during their escape from the god Typhon (You can guess how he rolled… In this case, the two were tied so as not to loose one another in the river Euphrates).

This constellation is reasonably large in visual real estate compared to other members of the Zodiac, but is occupied by fairly unremarkable stars, making Pisces one of the less prominent objects in the sky (it is possible you know the location of Pisces by looking below the more pronounced square of Pegasus). Pisces is made pronounced currently by its having caught Jupiter and Uranus at its Southern side, with Jupiter now making its way through Pisces (with a small fraction of time in Cetus) on its way into Aries this time next year. Most all observers will have Jupiter in their scopes at some point this Summer and Fall, giving them a chance to take in a second of the large gas giants in our Solar system as well as one solitary Messier Object within the Pisces boundary while having to move their scopes only slightly.

The only Messier Object within the Pisces boundary is M74, a less-pronounced cousin of the also face-on Whirlpool Galaxy (M51). In Hubble images (below), the bright cloudiness almost shrouds the spiral quality of the galaxy. An infrared image taken with the Spitzer Space Telescope (below) reveals a pronounced web-like quality to this galaxy, as well as some greater definition in the M74 spiral shape.

M74, image from NASA, ESA and the GMOS Commissioning Team.
Infrared image of M74 taken by the Spitzer Space Telescope.

For those attempting to check two planets of their list while memorizing the shape of Pisces, the image below provides you a reasonable cheat-sheet for how to hop from the very prominent (magnitude of -3) Jupiter ("1") to the markedly less prominent (magnitude 5.75) Uranus ("3"). You'll note in the image that the four famous Galilean Satellites of Jupiter (Ganymede, Io, Callisto, and Europa) are virtually on top of one another at this "magnification," giving you an idea of how far the motion will be to find Uranus in your eyepiece. From among the many (invisible) other moons of Jupiter (all of the labels in this image are just a fraction of the total count to date), you'll note a 6th magnitude star at position "2", the brightest other object in the sky in this area. A slow, cautious scope motion to your south-east (and low magnification to start) will help you capture a view of this small blue-ish globe, a fitting color to search for within this aquatic constellation.

Finding Uranus starting at Jupiter. Map generated with Starry Night Pro 6.

Clear skies, Damian

Some Light Science Reading. The Constellations: Aquarius

As first appeared in the October 2009 edition of the Syracuse Astronomical Society newsletter The Astronomical Chronicle (PDF).

Constellation Map generated with Starry Night Pro 6.

Of all of the Constellations that have taken human forms through history, Aquarius the Water Bearer may have the most varied professional background. His career peaked early in human history, with the Babylonians identifying Aquarius as GU.LA, their identifier for the god Ea, Ea derived from the Sumerian god Enki. To put that into perspective, the stars of Aquarius have been recognized as a Constellation since, at the very least, 1200 B.C. (the dates of the oldest known Babylonian star catalogues. As these catalogues borrow heavily from Sumerian mythology, we can only assume his actual origins step significantly further back, although records are difficult to come by). His demotion to water bearer comes with his adoption by the Greeks and his inclusion into their mythology, with his aquatic status in Greek mythology traveling, albeit likely by land routes, as far East as India. Then, like a leisure suit-clad Pat Boone on his pre-heavy metal reinvention, Aquarius found considerable recent fame as a disco star. When one starts at the top, it would seem that careers, like water, run downhill (although he may not yet be ready for the Chinese Constellation Fenmu, the tomb composed of the upper-left set of his stars). Its importance to several cultures throughout history is of little surprise, as this collection of stars, like the other 11 members of the Zodiac, lies along the ecliptic, the perceived path of the Sun over the course of the year.

NGC 7293. From hubblesite.org

NGC 7009. From hubblesite.org

As of this writing, Aquarius and the waters spilling from his flask separate the planets Jupiter and Neptune (with Jupiter prominent in our night time sky in Capricornus) from Uranus, which lies just on the inside edge of the boundaries of Pisces. Within his borders lie several interesting objects for binocular and telescope viewers alike, including two Messier globular clusters (M2, M72), one Messier open cluster (M73), and two prominent NGC objects. Had the Helix Nebula (NGC 7293, left) been discovered in far more recent times instead of its 1824 origins, its name night instead be the Eye Nebula, a description more in line with the many Hubble and ground-based images generated in the past few years. The full-size image (HERE) is a sight to behold. The Saturn Nebula (right, NGC 7009) makes a nearly straight line with M72 and M73, making this a very dense patch of outstanding objects. Herschel documented its discovery in late 1782, but it took the Hubble telescope to again add to its fame as a beautiful and complex object.

While the star connection provided by Starry Night Pro (shown above) is as legit as any other, I found the connection pattern shown at right (from wikipedia) to perhaps be a bit easier to visualize as a human with a large jug, although this view is decidedly of a clumsier water bearer spilling the jug contents ahead of him (below). Someone should tell this version of him to not quit his day job.

Constellation Map generated with Starry Night Pro 6.

www.syracuse-astro.org
en.wikipedia.org/wiki/Aquarius_(constellation)
en.wikipedia.org/wiki/Babylon
en.wikipedia.org/wiki/Ea_(Babylonian_god)
en.wikipedia.org/wiki/Sumer
en.wikipedia.org/wiki/Constellation
en.wikipedia.org/wiki/Pat_Boone
en.wikipedia.org/wiki/Age_of_Aquarius
www.ianridpath.com/startales/aquarius.htm
en.wikipedia.org/wiki/Zodiac
en.wikipedia.org/wiki/Ecliptic
en.wikipedia.org/wiki/Sun
en.wikipedia.org/wiki/Jupiter
en.wikipedia.org/wiki/Neptune
en.wikipedia.org/wiki/Capricornus
en.wikipedia.org/wiki/Uranus
en.wikipedia.org/wiki/Pisces_(constellation)
en.wikipedia.org/wiki/Messier_2
en.wikipedia.org/wiki/Messier_72
en.wikipedia.org/wiki/Messier_73
en.wikipedia.org/wiki/Helix_nebula
hubblesite.org
upload.wikimedia.org/wikipedia/commons/b/b1/NGC7293_%282004%29.jpg
en.wikipedia.org/wiki/Saturn_Nebula
en.wikipedia.org/wiki/William_Herschel
en.wikipedia.org/wiki/Main_Page