Some Light Science Reading. The Constellations: Cetus

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

Constellation Map generated with Starry Night Pro 6.

There is a region of the Night Sky that is dominated by aquatic creatures. Alternately, if we consider empty space as its own kind of ocean, there are regions where the stars of the Aquatic Constellations appear to undulate at geologic time scales, making the current arrangement of stars effectively motionless to our eyes and those of many generations to come.

Within this Water Region are the Constellations (as listed at wikipedia) Aquarius, Capricornus, Cetus, Delphinus, Eridanus, Hydra, Pisces, and Piscis Austrinus. If we think in terms of seasonal change, this does seem like an oddity of planning. Who would place the Aquatic Constellations in the Night Sky during the late fall and winter, when the temperature in some parts of the Northern Hemisphere (such as at Darling Hill Observatory) might as well be that of interstellar space? Where are the polar bear and penguin Constellations?

Constellation Map generated with Starry Night Pro 6.

The answer to this has less to do with the apparent location of these Constellations in our Night Sky and more to do with the position of the Sun during our daytime sky roughly six months later (the Sun IN Pisces, for instance). When the Sun is in this region of the sky from our terrestrial perspective, the Northern Hemisphere is well into Spring, the time of the rainy season in our and ancient cultures. The image above shows the position of the Sun at noon on April 1, 2011. No joke. If our blue sky were to disappear, we'd have a few seconds to enjoy the daytime Constellations (before we passed out, were cooked by radiation, or froze to death, depending on where the atmosphere went. Fun factoid – Mercury, with no atmosphere to speak of, provides 24-hour Constellation observing!).

This brings us to Cetus, formerly known as a sea monster (indirect evidence for the lack of submarines in ancient Greece?), now increasingly considered to be a whale (perhaps equally terrifying to a small boat far from land in antiquity). Like some misidentified sea monster seen from a dry beach by a hydrophobic observer, Cetus provides a small amount of clear identification and several subtle treats for Earth-locked amateur astronomers that leave quite a bit to the imagination.

Constellation Map generated with Starry Night Pro 6.

One of the patient treats in Cetus is the variable multiple star Mira (Omicron Ceti). As our Observatory Director Ray Dague pointed out at our last Public Viewing session, this star takes its own 331.65 day journey from a 10.1 magnitude star to a 2.0 magnitude star. That is a phenomenal change! It is current at 6.5 magnitude and found in the neck of the beast (above).

M77 image by Hunter Wilson.

As for Messier Objects, those objects one can definitely say they saw on first pass with even moderately-sized binoculars, Cetus is accompanied by only M77, a distant (47 million light years away) barred spiral galaxy (at left, photo by Hunter Wilson). While one distant galaxy is anchored in this part of the sky, this small region is host to tens-of-thousands of invisible objects swimming around our Sun. Cetus is a border Constellation to the Zodiac, those 12 Constellations that mark the path of the Sun and planets from our observing post on Earth. By the way the borders are drawn, Cetus does play host very occasionally to planets and, notably, the objects of the Asteroid Belt. Cetus had the distinction of being the host to 4 Vesta (shown below, photo from the Hubble Space Telescope), the 2nd largest object identified in the Asteroid Belt, during its discovery on 29 March 1807 by Heinrich Wilhelm Olbers.

4 Vesta (Images taken 2007 May 14 and 16). From hubblesite.org.

And then there's stuff we can only imagine seeing without the most powerful scopes in the known universe. Cetus is the host to JKCS 041 (shown below, also in the neck as marked in the opening image. Must be a hungry monster), the current holder of the title as most distant galaxy cluster yet discovered, residing at a boggling distance of 10.2 billion light years from us. Wikipedia hosts a short little movie about this distant cluster HERE.

JKCS 041 (22 Oct 2009) from NASA/CXC/INAF/S.Andreon et al Optical: DSS; ESO/VLT.

Clear skies, Damian

P.S. It has taken all my concentration to not refer to Cetus as a Whale of a Constellation.

Some Light Science Reading. The Constellations: Libra

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

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…

Gliese 581

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.