Arc second
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Revision as of 10:36, 2 July 2007 by Domesticated om (Talk | contribs)
An arc second is the divisions of a DEGREE, which is the primary unit of measure in the sky. A degree is subdivided into minutes and seconds. Thus, 60 arc minutes equals one degree and 60 arc seconds equals one minute. The size of a planet in the sky is usually measured in arc seconds (Example: Uranus is 3.6 arc seconds in diameter).
