- noun the temporary complete or partial disappearance of a celestial body when another moves between it and an observer
- The cutting off of an astronomical body from an observer by some other body. The most usual is an occultation of a star by the Moon. Occultations are a fruitful source of astronomical data, yielding precise positions (e.g. of the Moon in its orbit) and other information. Occultations of stars by asteroids allow asteroid sizes to be determined, and the ring systems and atmospheres of the outer planets can be investigated by observing the dimming of starlight as the planet passes in front of a star.