any asteroid, comet, or meteoroid whose orbit intersects that of the Earth and has the potential to collide with Earth; abbr. NEO
NASA has a congressional mandate to catalog all near-Earth objects.
A comet or asteroid with an orbit or trajectory that comes near Earth's orbit, often drawn into such a path by the gravitational effect of the Earth and other planets. While there is currently no known near-Earth object on a collision course with Earth, collisions with such objects have taken place in the past and may be associated with mass extinctions such as those that took place at the end of the Permian and Cretaceous Periods.