The passage of one astronomical body in front of another, usually the obscuration of a star by the Moon; strictly speaking, a solar eclipse, when the Moon passes in front of the Sun, is a special form of occultation. Precise timings of lunar occultations of stars help to refine our knowledge of the Moon’s orbit. Occultations of stars by asteroids and planetary satellites can provide improved diameters for the occulting bodies. The Galilean satellites of Jupiter are regularly occulted by the planet. Jupiter’s satellites may occult one another when Earth lies close to their orbital plane. See also Grazing Occultation.