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  3. Near-Earth Object
Planetary Science

Near-Earth Object

Definition

Any small solar system body whose orbit brings it close to Earth, with a perihelion distance less than 1.3 AU. Includes near-Earth asteroids and comets. NASA's Planetary Defense Coordination Office tracks potentially hazardous NEOs larger than 140 meters.

Related Terms

Asteroid

A small rocky body orbiting the Sun, primarily found in the asteroid belt between Mars and Jupiter. Asteroids range from...

Comet

An icy small body that, when passing close to the Sun, releases gases in outgassing, producing a visible coma and someti...

Orbit

The curved path of a celestial object around a star, planet, or moon under gravity's influence. Orbits can be circular, ...

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