near-Earth asteroid

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Learn how we discover near-earth asteroids and the paths they travel in space

near-Earth asteroid

astronomy

Also known as: Earth-approaching asteroid, IEO asteroid, interior-to-Earths-orbit asteroid(Show More)

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July 1, 2026

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Learn how we discover near-earth asteroids and the paths they travel in space — Learn how we discover near-earth asteroids and the paths they travel in space Learn how scientists find and track near-Earth asteroids, which are asteroids that might pass close to Earth's orbit.

Near-Earth asteroids (NEAs) are asteroids whose orbits bring them close to Earth. While not all NEAs cross Earth's orbit, they are categorized based on their proximity to Earth and Mars. These categories include Mars crossers, Amors, Apollos, Atens, and Atiras.

NEAs pose a potential danger due to the possibility of collision with Earth. The impact hazard depends on the object's mass and velocity, with larger objects capable of causing global catastrophes. Scientists actively conduct search programs to detect and track these objects, assessing their threat level using scales like the Torino Impact Hazard Scale. Efforts are also underway to develop planetary defense strategies to mitigate potential impacts.12

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asteroid
Near-Earth asteroids
Asteroids that can come close to Earth are called near-Earth asteroids (NEAs), although not all NEAs actually cross Earth’s orbit. NEAs are divided into several orbital classes. Asteroids belonging to the class most distant from Earth—those asteroids that can cross the orbit of…
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Asteroids that can come close to Earth are called near-Earth asteroids (NEAs), although not all NEAs actually cross Earth’s orbit. NEAs are divided into several orbital classes. Asteroids belonging to the class most distant from Earth—those asteroids that can cross the orbit of…
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Earth impact hazard
Objects that pose a threat
Like short-period comets, most known Earth-approaching asteroids have orbits tilted by less than 20° to the plane of the solar system and periods of less than about three years. Long-period comets have orbital periods greater than 200 years and usually much greater; they can approach from any direction.
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Like short-period comets, most known Earth-approaching asteroids have orbits tilted by less than 20° to the plane of the solar system and periods of less than about three years. Long-period comets have orbital periods greater than 200 years and usually much greater; they can approach from any direction.
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Eros
…member of a group called near-Earth, or Earth-approaching, asteroids, Eros can pass within 22 million km (14 million miles) of Earth. During a close approach in the 1930s (before the development of direct radar ranging), astronomers were able to observe the asteroid’s parallax displacement against the background stars to refine…
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…member of a group called near-Earth, or Earth-approaching, asteroids, Eros can pass within 22 million km (14 million miles) of Earth. During a close approach in the 1930s (before the development of direct radar ranging), astronomers were able to observe the asteroid’s parallax displacement against the background stars to refine…
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planetary defense
…of or to destroy such dangerous asteroids. It was determined that the most dangerous asteroids were those with a diameter larger than 1 km (0.6 miles), the so-called “planet-killer” asteroids. Congress then asked NASA to find at least 90 percent of such asteroids by 2010. NASA did so, but, in…
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…of or to destroy such dangerous asteroids. It was determined that the most dangerous asteroids were those with a diameter larger than 1 km (0.6 miles), the so-called “planet-killer” asteroids. Congress then asked NASA to find at least 90 percent of such asteroids by 2010. NASA did so, but, in…
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small body
Populations
…(1) most observed comets, (2) near-Earth asteroids, most with orbits that cross either Earth’s orbit or Mars’s orbit and some with orbits that lie mostly or entirely inside Earth’s orbit and cross the orbits of Venus or of both Venus and Mercury while closely approaching Earth’s, (3) Centaur objects, icy…
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…(1) most observed comets, (2) near-Earth asteroids, most with orbits that cross either Earth’s orbit or Mars’s orbit and some with orbits that lie mostly or entirely inside Earth’s orbit and cross the orbits of Venus or of both Venus and Mercury while closely approaching Earth’s, (3) Centaur objects, icy…
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