Jimmy Westlake: Spot Corvus and Crater in our spring sky
April 21, 2014
Steamboat Springs — Winging his way across our springtime sky is a delightful little constellation named Corvus, the Crow.
The four main stars of Corvus form an unmistakable kite-shaped pattern located one-third of the way up in our southern sky about 10 p.m. in late April. The distinctive pattern makes Corvus easy to spot.
Corvus' four brightest stars, starting at the top and proceeding clockwise, are Algorab, Gienah, Minkar and Kraz. Minkar marks the crow's head; Algorab, his tail; and Gienah and Kraz represent the tips of his wings.
In most constellations, the designation Alpha is bestowed upon the brightest star, but Corvus is a notable exception. In 1603, Johannes Bayer gave the Alpha distinction to Alchiba, a faint little star that marks the Crow's beak, just below Minkar.
Is this evidence that the star was once much brighter in our sky and has faded throughout the centuries? Maybe, but no one knows.
Corvus is pictured in the sky as trying to steal a sip of water from Crater, the Cup — his neighboring constellation to the west. Crater's stars are fainter than those of Corvus, but the goblet-shaped pattern is unmistakable. Both of these constellations are precariously balanced on the back of Hydra, the Water Snake.
There is a single Greek legend that links all three of these constellations together.
In it, Corvus is the beloved pet bird of the sun god, Apollo, whose day job was driving the fiery chariot of the sun across the sky. One hot summer day, Apollo grew very thirsty and sent his beautiful white-feathered bird Corvus to fetch a drink of water from a nearby well. The bird flew off with the best of intentions, carrying Apollo's cup, but along the way to the well, Corvus was distracted by a fig tree and stopped to eat his fill of the sweet fruit.
Realizing that he had tarried too long and that his master would be angry, Corvus concocted an alibi. He scooped up a scrawny little water snake in his beak and flew back to Apollo with the empty cup, explaining that the water snake had prevented him from reaching the well.
Apollo was furious at this feeble lie and cursed the bird so severely that his white feathers turned jet black. He then tossed all three, the Crow, the Cup and the Water Snake, into the sky and transformed them into stars. There, Corvus, the Crow, suffers eternal thirst as Hydra, the Water Snake, prevents him from drinking any water from Crater, the Cup.
Finding Corvus in the sky is as easy as one, two, three. Just use the curved handle of the Big Dipper: Follow the arc of the handle to the bright star Arcturus, then spike on to the bright star Spica and continue to Corvus.
Professor Jimmy Westlake teaches astronomy and physics at Colorado Mountain College’s Alpine Campus. His “Celestial News” column appears weekly in the Steamboat Today newspaper, and his “Cosmic Moment” radio spots can be heard on local radio station KFMU. Check out Westlake’s astrophotography website at http://www.jwestlake.com.
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