page_title: Big Dipper
section_title: Stars
hierarchical_section_title: Big Dipper / Stars
caption_attribution_description: English: The Big Dipper (Ursa Major) photographed by Prof. Chen Hualin in Dakawa, Morogoro, Tanzania at midnight on February16,2018.
context_page_description: The Big Dipper or the Plough is a large asterism consisting of seven bright stars of the constellation Ursa Major; six of them are of second magnitude and one, Megrez, of third magnitude. Four define a "bowl" or "body" and three define a "handle" or "head". It is recognized as a distinct grouping in many cultures. The North Star, the current northern pole star and the tip of the handle of the Little Dipper, can be located by extending an imaginary line through the front two stars of the asterism, Merak and Dubhe. This makes it useful in celestial navigation.
context_section_description: Within Ursa Major the stars of the Big Dipper have Bayer designations in consecutive Greek alphabetical order from the bowl to the handle.
  In the same line of sight as Mizar, but about one light-year beyond it, is the star Alcor (80 UMa). Together they are known as the "Horse and Rider".  At fourth magnitude, Alcor would normally be relatively easy to see with the unaided eye, but its proximity to Mizar renders it more difficult to resolve, and it has served as a traditional test of sight. Mizar itself has four components and thus enjoys the distinction of being part of an optical binary as well as being the first-discovered telescopic binary (1617) and the first-discovered spectroscopic binary (1889).
  Five of the stars of the Big Dipper are at the core of the Ursa Major Moving Group. The two at the ends, Dubhe and Alkaid, are not part of the swarm, and are moving in the opposite direction. Relative to the central five, they are moving down and to the right in the map. This will slowly change the Dipper's shape, with the bowl opening up and the handle becoming more bent. In 50,000 years the Dipper will no longer exist as we know it, but be re-formed into a new Dipper facing the opposite way. The stars Alkaid to Phecda will then constitute the bowl, while Phecda, Merak, and Dubhe will be the handle.
caption: The Big Dipper (Ursa Major) photographed by Prof. Chen Hualin in Dakawa, Morogoro, Tanzania at midnight on February 16, 2018
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