| near-Earth object |
| An asteroid or comet in an orbit which makes it possible for the object to approach exceptionally close to the Earth. Most such objects are in orbits around the Sun with perihelia less than 1.3 AU and aphelia greater than 0.983 AU. Observed objects range in size down to tens of metres. They are believed to be asteroids from the main asteroid belt which have been perturbed by the gravitational attraction of the major planets, and the inactive nuclei of comets. |