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hour circle

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noun Astronomy.
  1. a great circle on the celestial sphere passing through the celestial poles and containing a point on the celestial sphere, as a star or the vernal equinox.
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Origin of hour circle

First recorded in 1665–75
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for hour circle

hour circle

noun
  1. a great circle on the celestial sphere passing through the celestial poles and a specified point, such as a star
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Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

hour circle in Science

hour circle

  1. A great circle passing through the poles of the celestial sphere and intersecting the celestial equator at right angles. An hour circle is equivalent to a meridian on Earth and is used in describing the position of a celestial body with respect to an observer's celestial meridian. See more at hour angle.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.