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A great circle on the celestial sphere having a plane that passes through the center of the earth and is parallel to an observer's horizon. Also called rational horizon.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
(Astronomy) See horizon2b
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
1. the line or circle that forms the apparent boundary between earth and sky.
a. the small circle of the celestial sphere whose plane is tangent to the earth at the position of a given observer, or the plane of such a circle (sensible horizon).
b. the great circle of the celestial sphere whose plane passes through the center of the earth and is parallel to the sensible horizon of a given position, or the plane of such a circle (celestial horizon).
3. the limit or range of perception, knowledge, or the like.
4. Usu., horizons. the scope of a person's interest, education, understanding, etc.
5. a thin, distinctive geological stratum useful for stratigraphic correlation.
6. any of the series of distinctive layers found in a vertical cross section of any well-developed soil.
[1540–50; < Latin horizōn < Greek horízōn(kýklos) bounding (circle), present participle of horízein to bound, limit]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
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|Noun||1.||celestial horizon - the great circle on the celestial sphere whose plane passes through the sensible horizon and the center of the Earth|
great circle - a circular line on the surface of a sphere formed by intersecting it with a plane passing through the center
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