What's the Difference Between an Asteroid and a Meteor?

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Today, we dealt with an asteroid and a meteor. The 2012 DA14 asteroid zipped passed Earth today and a meteor exploded over Russia. What the heck is the difference between an asteroid and a meteor? And a meteorite? And a meteoroid? Not too much, apparently!

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An asteroid is a rocky object in space that's not as big as a planet and isn't a moon. There are millions of them, think the asteroid belt in space. A meteor is an asteroid that burns up as it enters the Earth's atmosphere, think shooting stars. A meteorite is a meteor that actually lands on the surface of Earth, think about Russia today.

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As for a meteoroid? No one really knows. They're just kind of like smaller asteroids. [Space, Image by Don Davis via NASA]

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DISCUSSION

Asteroids are small Solar System bodies that are not comets. The term asteroids historically referred to objects inside the orbit of Jupiter. They have also been called planetoids, especially the larger ones. These terms have historically been applied to any astronomical object orbiting the Sun that did not show the disk of a planet and was not observed to have the characteristics of an active comet, but as small objects in the outer Solar System were discovered, their volatile-based surfaces were found to more closely resemble comets, and so were often distinguished from traditional asteroids.[1] Thus the term asteroid has come increasingly to refer specifically to the small bodies of the inner Solar System within the orbit of Jupiter, which are usually rocky or metallic. They are grouped with the outer bodies—centaurs, Neptune trojans, and trans-Neptunian objects—as minor planets, which is the term preferred in astronomical circles.

A meteorite is a meteoroid (a solid piece of debris from such sources as asteroids or comets) originating in outer space that survives impact with the Earth's surface. A meteorite's size can range from small to extremely large. Most meteorites derive from small astronomical objects called meteoroids, but they are also sometimes produced by impacts of asteroids. When a meteoroid enters the atmosphere, frictional, pressure, and chemical interactions with the atmospheric gasses cause the body to heat up and emit light, thus forming a fireball, also known as a meteor or shooting/falling star. The term bolide refers to either an extraterrestrial body that collides with the Earth, or to an exceptionally bright, fireball-like meteor regardless of whether it ultimately impacts the surface.

Source: Wikipedia. I thought it would be helpful to put the two together for your benefit, and to point to a source of info which in most cases will resolve these sort of questions.