occultation

Definition

An astronomical event that occurs when one celestial object is hidden by another celestial object that passes between it and the observer when the nearer object appears larger and completely hides the more distant object.

Etymology

From Latin occultātiōnem, accusative singular of occultātiō (“concealment; insinuation”), from occultāre, present active infinitive of occultō (“to conceal, hide”); analysable as occult + -ation.

Example Sentences

• "[T]he diſtance of any place within this kingdom from it, will not much vary the manner of their Appearance in any of the Phænomena, except the Eclipſe of the Sun: for, in the Occultations, the Stars will appeare to paſs nearly under the ſame Angles and Spots of the Moon; […]"
• "The bright star Aldebaran is to be occulted by the moon on December 20th, at about 5 o'clock pm. Aldebaran is said to be eight hundred and eighty times the mass of the sun, with a diameter of over 8,000,000 miles; a distance so great that a meteor traveling at the rate of thirty miles per second, would require over three days to cross the disk of the star. Yet, notwithstanding the immense volume, the accultation will occur in a moment, so great is the distance of the star from us, and will continue for about one hour and eight minutes."
• "Stellar occultations potentially provide the highest precision data for relating solar system ephemerides to the stellar reference frame. For example, occultations by the Uranian rings can define the position of the occulted star relative to the rings to better than 0.02 mas (equivalent to a few hundred meters at the distance of Uranus). Occultations by atmospheres can be less precise than occultations by symmerical solid bodies, like rings and large asteroids, with a precision on the order of 1.0 mas."

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