May: Dipper Directions

May 2010

Dipper Directions

By Calvin L. Chrisman

Even if you don’t recognize much in the night sky, you probably can point out the Big Dipper. The Big Dipper is technically not a constellation. It is what is known as an asterism – a recognizable shape in the sky that is part of a bigger constellation. The Big Dipper is part of Ursa Major, the Big Bear. Ursa Major covers a lot of sky. The tail of the bear is the handle of the dipper and the cup of the dipper makes up part of the body. Its legs are quite long, and, to me, it looks more like a big giraffe. Oh well. The point is the Big Dipper. From our position in Western North Carolina, it is always above the horizon at any time of the year and at any hour. This is not true of all star formations which rise and set during the night and disappear entirely during certain seasons.

Although the Big Dipper is always visible, it is sometimes easier to spot than at others and May is a great time to take a look. The Big Dipper is interesting to see, but also a useful pointer for finding other stars and constellations. If you face north in the late evening early in the month or just after sunset late in the month, you will see the Big Dipper. First, follow the lip of the dipper out by five times the distance between the stars that make up the lip. This will bring you to Polaris, the North Star. It is located almost over Earth’s geographic North Pole. Now look again at the Dipper and you will see its handle prominently pointing toward the east. Follow the arc of the handle until you come to a bright yellow-orange star. This is Arcturus in the constellation Bootes, the herdsman. Bootes was said by the ancient Greeks to have been rewarded by the gods with a place in the sky for having invented the plow. The name Arcturus in Greek means guardian of the bear. Arcturus is a very bright star and is only thirty seven light years away from our Sun. Remember to arc to Arcturus.

If you continue the arc from the handle of the Dipper past Arcturus, you will come to a bright blue-white star called Spica. The reminder is to arc to Arcturus and continue to Spica beyond. Spica is almost exactly first magnitude and is in the constellation Virgo. Virgo is the only female figure among the constellations and has been associated with many goddesses. She is usually seen as holding the scales of justice represented by Libra, the adjoining constellation, or she is seen holding an ear of wheat. Spica represents this ear of wheat.

At this time of the evening, Spica is on the meridian which is an imaginary line extending from north to south and passing though the zenith, the point directly overhead. As you look at Spica, you will be facing south. As you look to your right, or west, you will see a line or equally bright objects starting with Saturn then Regulus, the bright variable star in Leo the lion, continuing to red-orange Mars and ending with Pollux, one of the twins in Gemini. Enjoy the sight of the bright, beautiful stars and planets during the month of May.

Clear Skies!

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