- a comet or asteroid pushed by the gravitational attraction of nearby planets into an orbit that allows it to enter the earth's orbit and thereby pose a danger of collision. Abbreviation: NEO
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
- 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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.