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
Claimed moons of Earth Sun (not Earth) on the same orbital path as Earth, and appear to lead or follow Earth along the same orbital path. Other small natural objects in orbit around the Sun may enter orbit around Earth for a short amount of time, becoming temporary natural satellites. , the only confirmed example has been in Earth orbit during 2006 and 2007, though further instances are already predicted. The first major claim of another moon of Earth was made by French astronomer Frédéric Petit, director of the Toulouse Observatory, who in 1846 announced that he had discovered a second moon in an