Tuesday, 6 December 2011

Constellation-Big Dipper



Big Dipper is a group of seven bright stara thet form a pattern of a handle and as bowl. Orian and Big Dipper show the North Pole.

It resembles a big ladle .It is also use to guide other stars in the Northen Hemisphere. Polaris the North Star is found by drawing the imaginary line between the two stars at the end of the bowl which are called Pointer Stars as a line drawn between points to Pole Star.The big dipper is a circumpolar constellation so stay above the horizon all the night as it apperantly rotates around Polaris due to Earth's rotation.


A Greek story (the Big Bear was so-called before Homer) explains that Zeus fell in love with a mortal woman named Callisto, who was a far-traveler and a huntress. His wife Hera became jealous, and changed Callisto into a large bear. When Callisto failed to return after a long journey, her son Arcas set out to find her, and in a forest one day met a huge bear. To his horror, the bear started to run toward him. Not perceiving it was his mother, Arcas fitted an arrow to his bow and was about to slay the bear, when Zeus, to avert the impending tragedy, changed Arcas into a smaller bear (he could not undo the spell of Hera). Then Zeus grabbed both bears by the tails, swung them around (thus stretching their tails out), and hurled them into the sky where they would be safe and immortal. However, Hera had the last word, moving them to the portion of the sky that never sets, so that until the end of the world Callisto and Arcas must endure


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