Nadir
2903625
224777260
2008-07-10T11:03:13Z
Bobo192
97951
Reverted edits by [[Special:Contributions/58.27.192.9|58.27.192.9]] ([[User talk:58.27.192.9|talk]]) to last version by Apoc2400
{{dablink|For other uses, see [[Nadir (disambiguation)]].}}
{{wiktionarypar|nadir}}
[[Image:Zenith-Nadir-Horizon.svg|thumb|right|Diagram showing the relationship between the [[Zenith]], the Nadir, and different types of [[Horizon]]. Note how the Nadir is opposite the Zenith.]]
The '''nadir''' (from [[Arabic language|Arabic]] '''ندير''' ''nadeer'' '''نظير''' ''nathir'', "opposite") is the [[astronomy|astronomical]] term for the point directly below the observer, or more precisely, the point with an inclination of −90°. In simple terms, if you are standing on the Earth, it is the direction "down" toward your feet.<ref>{{cite web|url=http://www.merriam-webster.com/dictionary/nadir|title=Nadir definition|publisher=[[Miriam Webster]]'s Online Dictionary|accessdate=2008-04-23}}</ref>
Geometrically, it is the point on the [[celestial sphere]] intersected by a line drawn from the observer's location on the Earth's surface through the center of the Earth. The point opposite the nadir is the [[zenith]]. Nadir also refers to a downward-facing viewing angle of an orbiting [[satellite]]<ref>{{cite web|url=http://spacecraft.ssl.umd.edu/design_lib/ICES01-2435.ISS_CBM.pdf|title=The Common Berthing Mechanism (CBM) for International Space Station|publisher=Society of Automotive Engineers, Inc.|date=2001|accessdate=2008-04-23}}</ref>, such as is employed during remote sensing of the [[Earth's atmosphere|atmosphere]], as well as when an [[astronaut]] faces the Earth while performing an [[Extra-vehicular activity|EVA]].
The word is also used figuratively to mean the lowest point of a person's [[spirits]]. <ref>{{cite web|url=http://encyclopedia.jrank.org/MOS_NAN/NADIR_Arabic_nadir_opposite_to_.html|title=Nadir definition|publisher=[[Encyclopedia Britannica]], 11th Edition|accessdate=2008-04-23}}</ref>
== References ==
{{reflist}}
[[Category:Arabic words and phrases]]
[[Category:Celestial coordinate system]]
[[Category:Technical factors of astrology]]
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[[ar:النظير]]
[[ast:Nadir]]
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