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occultation

 - 4 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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Science Dictionary
occultation   (ŏk'ŭl-tā'shən)  Pronunciation Key 
The passage of one celestial object in front of another, temporarily blocking the more distant object from view. Occultations can provide information about the existence and measurements of the obscuring object. For example, when an asteroid passes in front of a star, the star is temporarily obscured to an observer on Earth, thus revealing the presence and approximate size of the asteroid. In 1977, astronomers were able to identify the rings around the planet Uranus when the otherwise invisible rings were observed to occult a background star. Occultations have also led to the discovery of more distant objects in space, such as binary stars and extrasolar planets. Compare transit.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. 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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