Monday, May 14, 2012
Jimmy Westlake's Celestial News column appears monthly in the Steamboat Today.
Find more columns by Westlake here.
Solar eclipse is Sunday
Don’t forget the spectacular annular eclipse of the sun on Sunday. From Northwest Colorado, the eclipse begins at 6:23 p.m. Maximum eclipse occurs at 7:30 p.m., when the moon will have reduced the sun to a thin crescent shape, only 8 degrees above the west-northwest horizon. The partially eclipsed sun will then set at 8:22 p.m. Use approved solar filters only, like a No. 14 welder’s glass, to watch the eclipse safely.
Centaurs figured heavily in the mythology of the ancient Greeks — so much so that two of them are immortalized in the stars as our constellations of Sagittarius the Archer and Centaurus the Centaur. The legend of these half-man, half-horse beasts might have originated when someone long ago first saw humans on horseback and imagined them to be some sort of human-equine hybrid.
Centaurus is one of our most ancient constellations, first mentioned in Greek literature from the fourth century BC. It is thought to represent the centaur named Chiron. He was a wise old centaur that served as the personal tutor of Greek heroes like Hercules, Theseus and Jason.
During one of Hercules’ many rowdy scuffles, Chiron accidentally was nicked by one of Hercules’ poisoned arrows. Being immortal, Chiron could not die, but the agony of the wound was so severe that he begged Zeus to revoke his immortality. This Zeus did, and Chiron was mercifully allowed to die. Zeus then immortalized the image of Chiron among the stars as our constellation of Centaurus.
Twenty-five hundred years ago, the constellation of Centaurus could be seen in its entirety from mid-northern latitudes, but the slow wobbling of the Earth on its axis has since carried the stars of the Centaur so far south that we can see only his human half from Colorado.
Go outside around 11 p.m. in mid-May (10 p.m. in late May) and look due south, underneath the bright blue star Spica and the nearby planet Saturn. There you’ll spot the Centaur’s triangular head, his arms and his human torso, but his equine body remains hidden from view.
One of the many celestial treasures found within the boundaries of Centaurus is the largest and most beautiful of the globular star clusters, Omega Centauri. There are at least 200 globular star clusters buzzing around the Milky Way like bees around a hive, and Omega Centauri is like the queen bee. As large as the full moon and containing millions of stars, Omega Centauri is visible to the unaided eye as a fuzzy ball and, when viewed through a telescope, is nothing short of breathtaking.
To see this cosmic wonder from Colorado, one must have a clear view all the way down to the southern horizon, because Omega manages to rise only a few degrees into our sky. Try climbing a hill or mountain with a clear view to the south and aim your binoculars at Omega. You won’t be disappointed.
Jimmy Westlake teaches astronomy and physics at Colorado Mountain College’s Alpine Campus. Check out his website at www.jwestlake.com.