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Ursa Maior



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Abbreviation:
UMa
English name:
Great Bear
Coordinates
see Stellar data

Particulars:


General:

Constellation of the northern hemisphere; in central europe this constellation never touches the horizon.
Ursa Majoris is a good starting point to find other stars and constellation in the sky (see "how to find constellations"):
Following the line leading from alpha UMa to beta UMa, one can find easily the pole star (Polaris, alphastar of the Little Bear).
The constellation Charioteer (Auriga) can be found when following the line leading from delta UMa to alpha UMa. Its leading directly to alpha Aur (Capella).
Drawing a line from delta UMa to beta UMa and beyond, you will find alpha Gem (Castor in the constellation Twins).
This constellation is most famous for the asterism Big Dipper, build by the stars alpha UMa, beta UMa, gamma UMa, delta UMa, epsilon UMa, zeta UMa and eta UMa.
Additional image available:

  • Chart with deepsky objects

    Stars and objects

    The multiple star system zeta UMa (called Mizar - from the arabian word for girdle) belongs to the most famous multiple stars in the sky. It's brightness is about 2.4 mag; therefore under very good conditions it is possible for the naked eye to see the 4th mag. companion, called 'Alcor' or 80 UMa (otherwise a small binocular will help). In small telescops another 4th mag star becomes visible. Each of these stars is as well a spectroscopic binary.
    Xi UMa is a binary with an orbiting period of 60 years. At the point when they seemed to be farthest away from each other they can be viewed with smaller scopes (as it was the case 1975), but at their closest (in 1992) one needs at least an aperture of 15 cm to resolve the components.
    Even with smaller scopes M81 is worth for observing. On photographs it reveals one of the most beautiful spirals in the sky. Please check the Messier Database for more info about M81 and M82.

    Mythological Background:

    According to greek mythology one day the Godfather Zeus saw a beautiful girl, the nymph Callisto, and fell in love with her. But Callisto was one of the virgin followers of the virgin goddess Diana, the huntress. So Zeus took the form of Diana to approach Callisto and managed it to make love to her.
    Once Diana saw what had happened (Callisto was obviously pregnant, when Diana and all her nymphs take a bath), she send Callisto away. Even worse, Hera, the wife of Zeus heard about Callisto and her now born son Arkas and become terribly jealous. In her anger she turned her into a bear.
    Years later Callisto, still a bear, met her son Arkas, but was of course not recognized by him. In his fear Arkas tried to kill the bear, but Zeus himself took both of them an placed them between the stars and made them two neighbouring constellations.
    When Hera saw Callisto glittering with the stars she furiously went down to the ocean to meet Thethys and Oceanos. She told them the story and ask a favour: that the bear never ever is able to reach the water. And indeed, as said above, in the northern hemisphere, the constellation of the Great Bear never touches the ocean. (This story can be found in "Metamorphoses, book II" by the roman poet Ovid (Publius Ovidius Naso, 43 BC to 17 AC). Its's an intersting that he speaks of the seven stars of the Bear. This implies that in those times just the stars forming the asterism of the Big Dipper were meant to form the bear. Though these stars are even nowadays called the Great Bear, the constellation is a bit more extended.)



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    C. Kronberg --- 97/12/03 --- smil@agleia.de