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occultation

 - 3 dictionary results

oc⋅cul⋅ta⋅tion

  [ok-uhl-tey-shuhn]
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–noun
1. Astronomy. the passage of one celestial body in front of another, thus hiding the other from view: applied esp. to the moon's coming between an observer and a star or planet.
2. disappearance from view or notice.
3. the act of blocking or hiding from view.
4. the resulting hidden or concealed state.
Origin:
1375–1425; late ME < L occultātiōn- (s. of occultātiō) a hiding, equiv. to occultāt(us) (ptp. of occultāre to conceal, keep something hidden, freq. of occulere; see occult ) + -iōn- -ion
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2009.
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oc·cul·ta·tion   (ŏk'ŭl-tā'shən)   
n.  

  1. The act of occulting or the state of being occulted.

  2. Astronomy

    1. The passage of a celestial body across a line between an observer and another celestial object, as when the moon moves between Earth and the sun in a solar eclipse.

    2. The progressive blocking of light, radio waves, or other radiation from a celestial source during such a passage.

    3. An observational technique for determining the position or radiant structure of a celestial source so occulted: a lunar occultation of a quasar.


[Middle English occultacion, from Latin occultātiō, occultātiōn-, from occultātus, past participle of occultāre, frequentative of occulere, to conceal; see occult.]
The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2009 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Encyclopedia

occultation

complete obscuration of the light of an astronomical body, most commonly a star, by another astronomical body, such as a planet or a satellite. Hence, a total solar eclipse is the occultation of the Sun by the Moon. By carefully measuring the decrease in the intensity of some stars as they disappear behind the Moon, astronomers can determine their angular diameters and ascertain whether they are binary systems (a pair of stars in orbit around their common centre of gravity). Astronomers are able to determine the precise sizes and shapes of planets, asteroids, and satellites, in addition to the temperatures of planetary atmospheres, from occultations of stars. During a stellar occultation on March 10, 1977, astronomers unexpectedly discovered the rings of Uranus. Compare eclipse.

Learn more about occultation with a free trial on Britannica.com.

Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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