- occultation
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/ok'ul tay"sheuhn/, n.1. Astron. 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.[1375-1425; late ME < L occultation- (s. of occultatio) a hiding, equiv. to occultat(us) (ptp. of occultare to conceal, keep something hidden, freq. of occulere; see OCCULT) + -ion- -ION]
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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.* * *
Universalium. 2010.