Ursa Major, Ursa Minor


      Ursa Major and Ursa Minor, the Big Bear and Little Bear, are two of the most familiar constellations. For those of us at midnorthern latitudes, they can be seen during all seasons.

      In a Greek myth, Zeus, king of the gods, fell in love with Callisto. Together they had a son, Arcas. Zeus, in story, changed Callisto into a bear to protect her from the jealousy of his wife, Hera. When Arcas grew up, he almost shot his mother by mistake. Zeus protected Callisto by changing Arcas into another bear and by placing both bearsin the sky. He carried them up by their tails, which explains why the bears in the sky have such long tails. Hera, in her jealousy, convinced the sea-god Poseidon not to let the bears bathe in the sea. Indeed, Ursa Major and Ursa Minor are always above the horizon and thus visible in the sky at night.

      The Big Dipper and the Little Dipper make up only parts of the constellations Ursa Major and Ursa Minor, so they are considered asterisms rather than constellations. The star in the middle of the Bid Dipper's handle is a double star, as you can see with the naked eye if your eyesight is good. The brighter of the two stars is known as Mizar, and the fainter one is Alcor. The Native Americans called them a horse and rider. In a telescope, Mizar turns out to be double itself.

      Follow the Pointers of the Big Dipper to Polaris, the North Star, which is at the end of the handle of the Little Dipper. Polaris is the closest bright star to the celestial north pole, only about 1o away from it (twice the diameter of the moon, or half the width of your thumb at the end of your outstretched arm). Polaris orbits the pole once a day. The other stars in the Little Dipper between Polaris and the end of the bowl are hard to see.


Last Update : 200598

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