A near-Earth object (NEO or if specifically an asteroid, near-Earth asteroid or NEA) is an object, such as a comet or asteroid, in solar orbit that passes near Earth. An Earth-crossing asteroid (ECA) is an asteroid whose orbital path crosses that of Earth. A fast moving object (FMO) is an observed astronomical object that appears moving very fast, undoubtedly a NEO. All these are of special interest because of the potential for a future impact with Earth (those most likely are termed potentially hazardous objects, PHOs, or if specifically asteroids, potentially hazardous asteroids, PHAs), and a number of surveys aim to identify them:
Near-Earth objects are also useful destinations for space probes, such as OSIRIS-REx visiting 101955 Bennu. Comets and asteroids passing close to Earth are among the easiest to reach.
NEOs are also classified according to a comparison of their orbits with that of Earth, each type referred to by the name of the first such asteroid discovered: