Jimmy Westlake: The strange Capricornus

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Jimmy Westlake

Jimmy Westlake's Celestial News column appears Tuesdays in the Steamboat Today.

Find more columns by Westlake here.

— The season of autumn is upon us. I know this because the Sea Goat has entered our early evening sky.

"What's a Sea Goat?" you ask.

Better known as our constellation Capricornus, the Sea Goat is a strange mythological beast that has the head and front feet of a goat, but the tail of a fish. Capricornus is the 10th constellation in the zodiac, sandwiched between Sagittarius the Archer and Aquarius the Water Carrier. Because most folks, including me, don't have a clue what a sea goat made of stars might look like, try looking, instead, for the outline of a large, fat boomerang, high in the southern sky at about 10 p.m. There are no stars in Capricornus brighter than third magnitude, but the distinctive boomerang shape makes it easy to spot anyway.

At the top right corner of the boomerang is a remarkable naked-eye double star named Algiedi (al-jee'-dee), the Arabic word for goat. The two stars do not form a true binary system, but are simply a chance alignment of unrelated stars. You can think of the twin stars of Algedi as being the horns of the goat. Just below Algiedi is the star Dabih (dah'-bee), an Arabic word meaning the forehead of the goat. At the left corner of the boomerang is the star Deneb Algiedi, Arabic for the tail of the goat, and just to the right of Deneb Algiedi is a star named Nashira. I've always thought that this was one of the loveliest star names in the whole sky. It's derived from the Arabic words that mean "fortunate one," or the "bringer of good tidings."

Hiding just above Nashira this year is the distant planet Neptune. Discovered 161 years ago in September 1846, Neptune has almost completed its first 164-year orbit of the sun since its discovery and is close to the same position in the sky that it was in 1846. Although binoculars are needed to even spot the faint planet, it is worth attempting. Not many people have seen Neptune with their own eyes. You will need a star chart that shows the location of Neptune so you can find it among all the other faint stars. I'd recommend doing an internet search for "Neptune Finder Chart 2007." You'll get several links to check out. If you have a telescope, you can actually see the blue-green disk of this distant planet, an unforgettable sight!

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 on the Web sites of CNN.com, NASA's "Astronomy Picture of the Day," Spaceweather.com, Space.com, Discover.com, , NationalGeographic.com, and in Sky & Telescope, Astronomy, Night Sky, Discover, and WeatherWise magazines.

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