Box 1: What are meteorites?
The Earth is constantly bombarded by material from space. Fortunately, most of this falls as tiny grains which burn up completely as they pass through the atmosphere, and are seen as meteors ("shooting stars").
Meteorites are exceptional - the few rocks from space which survive the journey through the atmosphere and land on the Earth's surface.
Some meteorites are similar to igneous rocks on Earth, others are pieces of metal, and others are different from all known Earth rocks. Almost all meteorites are fragments from asteroids. They have the same age as the solar system; approximately 4.5 billion years old. They contain important evidence which helps us to construct theories about the origin and history of the solar system.