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 These have been called, inaccurately but provocatively, "second", "third" or "other" moons of Earth. , an asteroid discovered on 27 April 2016, is possibly the most stable quasi-satellite of Earth. As it orbits the Sun, appears to circle around Earth as well. It is too distant to be a true satellite of Earth, but is the best and most stable example of a quasi-satellite, a type of near-Earth object. They appear to orbit a point other than Earth itself, such as the orbital path of the NEO asteroid 3753 Cruithne. Earth trojans, such as , are NEOs that orbit the