A small, rocky or metallic body revolving in interplanetary space around the Sun. A meteoroid is significantly smaller than an asteroid, ranging from small grains or particles to the size of large boulders. The clustered meteoroids associated with regular annual meteor showers are believed to be very small particles of cometary debris. Meteoroids that survive their passage through the Earth's atmosphere and land as meteorites are somewhat larger, solitary bodies and are encountered in no predictable pattern. See Note at meteor.
Meteoroids are lumps of rock or iron that orbit the sun, just as planets, asteroids, and comets do. Meteoroids, especially the tiny particles called micrometeoroids, are extremely common throughout the solar system. ... Other meteoroids are the debris that comets shed as they travel through space.
Colours of meteors depend on the relative influence of the metallic content of the meteoroid versus the superheated air plasma, which its passage engenders:
Orange-yellow (sodium)
Yellow (iron)
Blue-green (magnesium)
Violet (calcium)
Red (atmospheric nitrogen and oxygen)
It is estimated that probably 500 meteorites reach the surface of the Earth each year, but less than 10 are recovered. This is because most fall into the ocean, land in remote areas of the Earth, land in places that are not easily accessible, or are just not seen to fall (fall during the day).
Some facts about meteroids:
1) If a meteoroid is more than 10 metres in diameter, it is classified as an asteroid.
2) Around 500 meteorites are thought to reach the Earth’s surface every year but only five or six of those are recovered for scientists to study.
3) According to a study in 1985, a meteorite will hit a human being about once every 180 years.
4) When a meteoroid hits the Earth’s atmosphere, it may be travelling at 130,000mph.
5) It is illegal to buy or sell meteorites in South Africa.
6) A foot-thick coating of Kevlar protects the International Space Station from meteoroids.
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