Meteorites are pieces of rock or metal from space that survive their passage through the Earth's atmosphere and land on the Earth's surface. In space these bodies are called meteoroids. When they enter the atmosphere at high speed, they make the air glow and produce a luminous phenomenon, the meteor. If it is particularly bright, it is called a fireball or bolide. The vast majority of meteoroids burn up completely. Only larger and solid fragments are slowed down strongly and reach the ground. Only then are they called meteorites.
Most meteorites are fragments of asteroids from the asteroid belt between Mars and Jupiter. A few come from the Moon or from Mars. Many are around 4.6 billion years old and therefore as old as the solar system itself. This makes them valuable witnesses from the time the planets formed.
There are three main groups:
- Stony meteorites are by far the most common. They include the chondrites with their typical small silicate spheres (chondrules).
- Iron meteorites consist mainly of an alloy of nickel and iron.
- Stony iron meteorites are a rare mixed form, for example the pallasites with olivine crystals in a metal matrix.
Freshly fallen meteorites can often be recognized by a thin, dark fusion crust that forms during the flight through the atmosphere. Meteorites are named after the place where they were found.
