Water on Earth was brought here by meteorites. Life on Earth was most likely brought here by carbonaceous meteorites. In the book, you will learn to recognize meteorites and to tell them apart from Earth rocks. You will learn where they come from, how old they are, and where to go hunt for them. Finally, we will introduce you to some of the most famous meteorites. Only twenty years ago, few people thought it was possible to own a piece of space, and even fewer believed that someday you would be able to touch, or even own, a piece of the Moon or Mars, but we do know now that about 50 meteorites from the Moon, and about the same number of meteorites from Mars, have been found right here on our planet.
Meteorites are by definition extraterrestrial objects that landed on Earth. About 100,000 tons of those objects fall to Earth every year, but 90% of them weigh less than one gram. In fact, although they have been preserved in mineral collections since the beginning of the nineteenth century, they were considered as just rocks until 1980. It was only then that scientists grasped the importance of those extraterrestrial rocks. Formed some 4.57 billion years ago, meteorites are the memory of the Solar System. Impacts are the most important geologic phenomenon in the Solar System. On the Earth, 95% of the species that have existed are now gone and five of the extinction periods are now connected with known major impacts. The dinosaurs are not the only ones to have disappeared after the fall of an enormous meteorite.