premise: A near-Earth object is shorted to NEO.
hypothesis: A near-Earth object ( NEO ) is any small Solar System body whose orbit brings it into proximity with Earth . By definition , a solar system body is a NEO if its closest approach to the Sun ( perihelion ) is less than 1.3 astronomical unit ( AU ) . NEOs include more than fourteen thousand near-Earth asteroids ( NEAs ) , more than one hundred near-Earth comets ( NECs ) , and a number of solar-orbiting spacecraft and meteoroids , large enough to be tracked in space before striking the Earth . In the United States and since 1998 , NASA has a congressional mandate to catalogue all NEOs that are at least 1 kilometer wide , as the impact of such an object would be globally catastrophic .