Near-Earth object focused on asteroids and short-period comets. CNEOS even restricts its definition of NECs to short-period comets—, 107 such objects have been discovered. , only 20 comets have been observed to pass within of Earth, including 10 which are or have been short-period comets. Two of these comets, Halley's Comet and 73P/Schwassmann–Wachmann, have been observed during multiple close approaches. The closest observed approach was 0.0151 AU (5.88 LD) for Lexell's Comet on July 1, 1770. After an orbit change due to a close approach of Jupiter in 1779, this object is no longer a NEC. The closest approach ever observed for
Man in the Moon then cooled, becoming smooth, basalt rock. The near side of the Moon, containing these maria that make up the man, is always facing Earth. This is due to a tidal locking or synchronous orbit. Thought to have occurred because of the gravitational forces partially caused by the Moon's oblong shape, its rotation has slowed to the point where it rotates exactly once on each trip around the Earth. This causes the near side of the Moon to always turn its face toward Earth. Man in the Moon The Man in the Moon refers to any of several pareidolic images of