Saturday, September 9, 2006
Summer is slipping away from us. I know this because the Sea Goat is entering our early evening sky. "What's a Sea Goat?" you ask. It's a good question.
Better known as our constellation Capricornus, the Sea Goat is a strange mythological creature that has the head and front feet of a goat and 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 myself, 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, just east of the Teapot asterism of Sagittarius. There are no stars in Capricornus brighter than third-magnitude, but the distinctive boomerang outline makes it easy to spot anyway.
At the top right corner of the boomerang is a naked-eye double star named Algedi, meaning the Goat. The two stars do not form a true binary system but are simply a chance alignment of unrelated stars. I imagine the twin stars of Algedi to be the horns of the sea goat. Just below Algedi is the star Dabih, meaning the Forehead of the Goat. At the left corner of the boomerang is the star Deneb Algedi, or the Tail of the Goat, and just to the right of Deneb Algedi is a star named Nashira. I've always thought Nashira is one of the loveliest star names in the whole sky. It is derived from the Arabic words that mean the Fortunate One, or the Bringer of Good Tidings.
Hiding within the boundaries of Capricornus this year is the distant planet Neptune. Discovered 160 years ago this month, Neptune has nearly 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 spot the faint planet, finding it is well worth the effort. Not many people have actually seen Neptune with their own eyes. You will need a star chart that shows the exact location of Neptune so you can pick it out among all of the other faint stars. I recommend doing an internet search for "Neptune Finder Chart 2006." You'll get several links to check out. Then, if you have a telescope that you can point at Neptune, you can actually see its blue-green disk - an unforgettable sight.