What is a Meteoroid?

A meteoroid is a solid object that moves in space. It is smaller than an asteroid and has a different composition than a comet. When they, enter Earth’s atmosphere they can heat up and appear as streaks of light.

What is a Meteoroid?

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A meteoroid is a solid object made of a similar composition to an asteroid but is much smaller in size. Meteoroids are defined by the International Astronomical Union as “a solid natural object of a size roughly between 30 micrometers and 1 meter moving in, or coming from, interplanetary space.” The dimensions listed are not upper and lower boundaries to the definition of a meteoroid, which is why the term "roughly" is used. Objects smaller than meteoroids are known as dust. Most meteoroids come from the asteroid belt, but some can come from other nearby bodies, like the Moon. The name comes from the Greek meteoros, meaning "high in the air". Meteoroids can be classified in two groups, iron or stony, based on their composition.

As the meteoroid falls through the atmosphere, the temperature can increase, causing it to emit light. These are also known as shooting or falling stars. The part of the meteoroid that survives the journey through the Earth’s atmosphere and ultimately hits the ground is known as a meteorite. It is estimated that tens of thousands of meteoroids hit the Earth’s surface every year, and many more burn up whilst travelling through the atmosphere. There has only been one recorded incident of one injuring someone. In 1954 a woman in Sylcauga, Alabama, had to be taken to hospital after a 20kg rock came through the roof of her house.

A meteor shower occurs when many meteoroids can be observed in the sky. As they are all traveling parallel to each other it appears as if they are all coming from one location. Extremely bright meteors are known as fireball. These are meteoroids that have a luminosity brighter than venus as the fall through the atmosphere.

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Meteoroid Key Terms

• Meteoroid - A space object that has a similar composition to an asteroid but is smaller


• Meteorite - The remains of a meteoroid after travelling through the Earth’s atmosphere


• Shooting Star - A bright trail of light caused by a hot meteoroid as it travels through the atmosphere