Big Dipper - astronomy.

Big Dipper - astronomy. Big Dipper, common name applied to a conspicuous constellation in the northern celestial hemisphere, near the North Pole. It was known to the ancient Greeks as the Bear and the Wagon and to the Romans as Ursa Major (the Great Bear) and Septentriones (Seven Plowing Oxen). The seven brightest stars of the constellation form the easily identified outline of a giant dipper. In Europe, the pattern is known as the Plow, Charles's (Charlemagne's) Wain, and the Wagon; among the Hindus, it represents the seven rishis, or holy ancient sages. Of the seven stars constituting the Big Dipper, six are of the second magnitude and one is of the third magnitude. Two of the second-magnitude stars, alpha (?) and beta (? ) Ursa Major, which form the outer edge of the bowl, point directly to the North Star, or Polaris, and hence are called the Pointers. At the bend of the handle of the Big Dipper is the readily visible double star known as Mizar, or zeta (z) Ursa Major. Mizar, the first visual double star discovered, consists of two components having magnitudes of 2.4 and 4, respectively. The brighter component was itself found in spectroscopic studies (1889) to be a double star; subsequently, in 1908, it was discovered that the other component also is a spectroscopic double. Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.