Occultations

In an occultation a nearer body blocks the observer's line of sight to a farther one. Nothing is darkened for anyone else, so the timing depends on where the observer stands. A star is a point at infinity, so the shadow it casts is a cylinder with the radius of the occulting body. That shadow lights nothing, but it is how these events are computed.

• Lunar occultations: the Moon occulting stars and planets, grazes along the Moon's limb, star catalogues, and the reduction of timings.
• Occultations by planets and minor bodies: asteroid and TNO shadow paths, Gaia astrometry, light curves and chords, and one planet occulting another.