Asteroid, comet and meteorite: these are the differences

Space is full of asteroids, comets and meteorites. Not everyone can explain the differences straight away. Therefore, we dedicate an article to this topic.

Asteroid, comet and meteorite: all celestial bodies in our solar system

All three terms refer to objects in our solar system.

• They differ in size, composition and their distance from the sun. However, there are no precise definitions regarding size.
• At the beginning of the emergence of space, so-called planetetesimals formed from liquid and star dust.
• Some of these planetesimals grew and developed into planets. What was left were asteroids and comets.

Asteroids: Similar orbit to Earth

Asteroids are celestial bodies that have formed in an orbit similar to that of our Earth. Asteroids are often referred to as minor planets or asteroids.

• An asteroid consists of solid substances, namely rock and metal.
• Most asteroids are located in the so-called asteroid belt between Mars and Jupiter.
• Since asteroids contain little or no volatile substances, unlike the comets, they do not form a tail. That is why these celestial bodies cannot be seen with the naked eye.

Comets are further from the sun

The comets formed further outside our solar system. Unlike asteroids, they do not consist of solid materials, but of dust and water or carbon monoxide, i.e. volatile substances.

• Since they are further away from the sun, where lower temperatures prevail, the volatile substances are frozen.
• If a comet approaches the "warmer" regions of space, these substances thaw and form the so-called "coma", a "bubble" around the celestial body.
• This "coma" also gives the comet its name. The bubble around the celestial body then forms the typical comet tail.
• Most comets are not visible to the naked eye from Earth. Halley's comet is an exception. It approaches Earth every 76 years and can then be seen. The last time was in 1986.

From meteorite to falling star

The smallest objects are the meteorites. They are quite small: they can be a few centimeters tall or a few meters. In any case, they are smaller than asteroids, although the boundary is not precisely defined here.

• Meteorites can be fragments after an asteroid or comet collision. But they also form from the dust of a comet's tail.
• As long as you are in space, the objects are actually called meteoroids. Only when they enter the earth's atmosphere do they become a meteor.
• The friction of the air creates air friction, which creates a plasma trace. The electrons begin to glow in it. That is what becomes visible as a shooting star.
• When a meteor finally hits Earth, what is left of it is called a meteorite.

In our next post, we'll stay in space and explain what a galaxy is.