Trojan asteroid

A Trojan asteroid is a chunk of rock, metal, and ice that shares an orbit with a planet. Trojans can inhabit two regions, 60 degrees ahead of or behind the planet. They are held in place by the combined gravitational pull of the Sun and the planet with which they share an orbit. Earth has two known Trojans. The giant outer planets may have thousands of them. Jupiter, for example, has at least 5,000. Many Trojans contain organic compounds. Similar compounds could have been incorporated into the young Earth, so the Trojans could tell us more about the development of life on our planet and the possibility of life on other worlds of the solar system.