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The Big Dipper is one of the two most prominent constellations in the northern sky, the other being Orion. What makes it so easy to locate in the northern sky is its distinctive shape of a square scoop with a long handle and the uniform brightness of its stars. Officially, the Big Dipper is not a full-fledged constellation, but only an asterism. An asterism is any readily identifiable pattern of stars that is not one of the 88 official constellations. The Big Dipper, or as it is known in England, the Plow, is part of the constellation Ursa Major, the Great Bear. The Babylonians, American Indians and the Greeks all referred to this constellation as a bear.
According to the Greeks, the Great Bear was originally Callisto, the King of Arcadia's daughter. After the god Zeus fell in love with Callisto, his jealous wife Hera turned her into a bear. Just before Callisto was about to be killed by her own son Arcas, who did not realize that this particular bear was family, Zeus snatched Callisto away and placed her in the heavens as Ursa Major. As we shall see later, putting things in the heavens was one of Zeus’ favorite pastimes. Later on, Arcas was also placed in heaven as Ursa Minor, the Little Bear. Hera was outraged by the great honor accorded to Callisto and her son. To gain revenge, she made a pact with the sea god that neither Ursa Major or Minor (the Big or Little Dippers) may even descend below the horizon into the sea and must eternally circle overhead.
The bright stars of the Big Dipper, alpha Ursae Majoris and beta Uursae Majoris, are the pointers because they point to Polaris, the Pole Star. To find Polaris, run your eyes in a straight line from beta Uursae Majoris to alpha Ursae Majoris and then to a spot directly above the northern horizon. Polaris has a magnitude of 2.0 and is by far the brightest star in the area. Polaris is placed at the end of the handle of the Little Dipper or Ursa Minor. The stars of the Little Dipper are dim and much more difficult to see than those of its big brother. They form the same shape as the Big Dipper after being contorted a bit.
The double star of zeta Ursae Majoris or Mizar/Alcor, has already been mentioned. The magnitude of the stars Mizar and Alcor are respectively 2.3 and 4.0.