What is the difference between an asteroid, a meteorite and a comet?


Sometimes, in conversations with people far from astronomy, I notice that people incorrectly use terms denoting various celestial bodies. Let’s understand the types of small celestial bodies together.

They are solid celestial bodies much smaller than planets, orbiting the Sun. Most of the asteroids are in

In addition, a significant part of the asteroids is located in the Kuiper belt beyond the orbit of Neptune, as well as in the vicinity of the L4 / L5 Lagrange points of various planets (primarily Jupiter).

The shape of the asteroids is wrong. Those asteroids that, under the influence of their own gravity, took a more or less spherical shape are now classified as

Asteroids consist mainly of stone and metals, although there are also ice, carbon and other asteroids.

Comets, like asteroids, revolve around the Sun. They differ from asteroids in their composition. Comets are composed of ice, dust, frozen gases (such as carbon dioxide), etc. Although some comets can have a rocky or partially rocky core.

It is believed that asteroids formed closer to the Sun (for example, in the asteroid belt), where it is difficult for water and gases to remain solid due to strong solar radiation. Comets, on the other hand, were formed at the outskirts of the system — in the Kuiper belt and the Oort cloud. This explains such differences in the compositions.

The main feature of the comet is


There is no consensus on what the size boundaries of the meteoroid are. Some scientists believe that if more than 10 meters, then it is already an asteroid, others — that the upper limit of the meteoroid size is 30 meters. With the lower limit of dimensions, it is a little easier — 1 millimeter.

When a meteoroid collides with the planet’s atmosphere, it begins to experience strong friction against atmospheric particles and quickly burns up in the atmosphere, leaving behind a bright trail of fire in the sky.

This footprint is called

Headlines such as «A meteorite is flying towards the Earth ….» are often found in the news, and are illiterate. While it «flies», it is either a meteoroid or an asteroid. Or even a comet (the Tunguska meteorite, according to most researchers, was just a comet). And the object will become a meteorite only if it reaches the surface of the Earth.