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Difference Between Asteroids & Meteorites

Both asteroids and meteorites originate in outer space. Asteroids are small planet-like bodies that orbit the sun, and known as planetoids or minor planets. The asteroid belt that lies between Earth and Mars contains hundreds of thousands of these planetoids. Sometimes asteroids fall out of orbit and hit the Earth, and then they become meteorites. However, not all meteorites are asteroids, and meteorites may be from the Moon or another planet.

Asteroids
- Asteroids are small rocky bodies that orbit the sun. Between Mars and Jupiter is the asteroid belt, thought to be a planet that broke apart. Asteroids are inactive, which means they do not have ongoing geologic processes, such as plate tectonics or active volcanoes. An asteroid can become a meteorite if it escapes from orbit and collides with Earth.
Meteorites
- Meteorites are meteoroids that have impacted the Earth's surface. A meteorite may in fact originate as an asteroid, but meteorites can also come from outside of the solar system. These rocky extraterrestrials can be iron, iron compounds, or stone. Iron meteorites comprise only about 10 percent of all meteorites and contain nickel, which tells scientists they are from outer space.
The Makeup of Asteroids and Meteorites
- Scientists once thought asteroids and meteorites consisted of the same materials: stone and iron compounds. However, spectral analyses showed a difference in the reflectance patterns between asteroids and meteorites. It turns out that space weathering, caused by the flow of high-energy ions and small particles, erodes the surface of an asteroid by vaporizing it, and then depositing a layer of film that makes the surface appear dark red. Common meteorites do not have this discoloration.
Why Scientists Study Asteroids
- Scientists study the asteroid belt to gain an understanding of the formation of our solar system and its planets. Asteroids within the asteroid belt between Mars and Jupiter consist of melted minerals. Asteroids from the outer solar system tend to be carbon. The largest asteroid in our solar system is Ceres, which is 580 miles in diameter.
The Asteroid Menace
- Most asteroids occupy the asteroid belt and orbit the sun in an elliptical orbit. However, some follow different orbits that may bring them into close proximity to Earth. Some scientists believe an asteroid impact caused the extinction of the dinosaurs about 65 millions years ago. Some scientists worry that another asteroid could hit the Earth and wreak havoc on our planet.

Astronomy