Ursa Major Constellation – The Big Dipper
The Big Dipper is the most recognizable constellations in the northern sky. The Big dipper is easy to spot, and it is well known because it points towards the star Polaris which was used for centuries by navigators to find true North. The Big Dipper’s shape looks like a giant cooking pot. It has the shape of a square scoop with a long handle which stand out clearly because of the brightness of its stars.
Officially, the Big Dipper is not recognized as constellation, but rather it is an asterism. An asterism is any readily identifiable pattern of stars that are not within the 88 official constellations. The Big Dipper is in fact a segment of a larger constellation called Ursa Major. Many civilizations have referred to this constellation as the bear. As such, Ursa Major is widely known as the “Great Bear”.
The Little Dipper, or Ursa Minor Constellations
According Greek mythology, the god Zeus fell in love with Callisto. She was the daughter of the King of Arcadia. Zeus’ jealous wife Hera turned Callisto into a bear. Callisto, while in bear form, later encounters her son Arcas. Arcas almost shoots the bear unknowing it was his mother. To avert the tragedy, Zeus turns them both into bears and put them the sky, forming Ursa Major and Ursa Minor. Callisto is Ursa Major and her son, Arcas is Ursa Minor – the “Little Bear”, or the “Little Dipper”. Zeus is known for putting things in the heavens.
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 Pole Star, or North Star
The bright stars of the Big Dipper, alpha Ursae Majoris and beta Uursae Majoris, serve as pointers because they direct us directly to Polaris the “Pole Star”, also called the “North Star” because it is positioned centrally above the north pole. This it is always in the direction of the true North. 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.
An interesting sight to look at with a telescope is on the second star on the handle of the Big Dipper (second from the end). The naked eye sees one star, but there are actually two stars there. A telescope will reveal the double star of zeta Ursae Majoris or Mizar/Alcor, each with a magnitude of 2.3 and 4.0 respectively.