The familiar W-shaped pattern of Cassiopeia the Queen twinkles in the northeastern sky this month as fall approaches.
Friday, September 11, 2009
Jimmy Westlake's Celestial News column appears Tuesdays in the Steamboat Today.
Find more columns by Westlake here.
Steamboat Springs Summer is slipping away from us, and the changing constellations are a sure sign of the approach of fall. The Big Dipper that rode high in the sky during the spring and summer evenings now is sinking into the northwest. The Summer Triangle, too, is migrating westward. A whole stage full of new constellation characters is rising in the east to take their places.
One of the first star patterns to catch your eye in the late summer and early fall is a distinctive group of five bright stars forming the shape of a letter "W" in the northeastern sky. This familiar pattern represents Cassiopeia, the queen. The five stars of the W-pattern form the outline of the queen's chair, hanging upside down in the sky. Why upside down?
Greek mythology explains that Cassiopeia is being punished for her boastful ways. She had a bad habit of doting on her beautiful daughter, Andromeda, and once went so far as to claim that Andromeda was more beautiful than the sea nymphs, who were the pride and joy of Poseidon, the mythological god of the sea. Poseidon punished Cassiopeia by placing her in the sky close to the pole star so that, as she rotates around the pole, she would spend half of the year upside down, clinging to her throne for dear life. Let this be a lesson to all the vain and boastful people out there.
The star Caph, at the top of the W, is the nearest of Cassiopeia's five main stars at a distance of 54 light years from Earth, while the star marking the middle of the W is the most distant at 613 light years. This star, simply referred to as Gamma, is the brightest unnamed star in the northern hemisphere. Perhaps it was much fainter centuries ago when the Greeks and Arabs were naming the stars. Gamma is known today to be an unpredictable variable star that occasionally increases dramatically in brightness. Most recently, in 1937, Gamma briefly brightened to rival the brightest stars in the sky, then faded to a very unimpressive third magnitude star before returning to its present second magnitude status.
From Northwest Colorado, Cassiopeia is a circumpolar constellation, which means that it never actually dips below the northern horizon. It just barely skims above the mountaintops to the north before rising high again. Cassiopeia's chair is diametrically opposite the North Star, Polaris, from the Big Dipper, so, one or the other star pattern is visible at all times. The Big Dipper dominates the spring sky, and Cassiopeia rules the autumn nights. Just follow the hazy band of the Milky Way northward to find that familiar W-shaped pattern of Cassiopeia.
And, while in the vicinity of Cassiopeia, check out that fuzzy patch of light just east of the star Segin at the left tip of the "W." It's the famous "Double Star Cluster," and it is beautiful as seen through binoculars.
Professor Jimmy Westlake teaches astronomy and physics at Colorado Mountain College's Alpine Campus. He is an avid astronomer whose photographs and articles have been published around the world. His "Celestial News" column appears weekly in the Pilot & Today, and his "Cosmic Moment" radio spots can be heard on local radio station KFMU. Also, check out Jimmy's astrophotography Web site at www.jwestlake.com.