Asteroids and meteorites

• There are billions of asteroids in the main asteroid belt, located between the orbits of Mars and Jupiter. • The asteroid belt is largely empty space, and a spacecraft may safely travel through it. • Hundreds of Trojan asteroids circle the Sun in the same orbit as Jupiter. These asteroids are located near the two Lagrangian points where the gravity of the Sun balances that of Jupiter. • The Earth resides in a swarm of asteroids. Many of these near-Earth asteroids travel on orbits that intersect the Earth's orbit, with the possibility of an eventual devastating collision with our planet. • Asteroids can be chaotically shuffled out of certain orbits in the main belt, and redirected into the inner solar system. • The asteroids are the pulverized remnants of former worlds that failed to coalesce into a single planet. • Groups of asteroids, known as families, have very similar orbits. The members of each family are the collision fragments of a larger object, which was itself much smaller than a major planet. • The combined mass of billions of asteroids is less than 5 percent of the mass of the Earth's Moon. • The largest body in the main asteroid belt, 1 Ceres, and the first to be discovered there, is about 950 kilometers across and contains about one-third of the total mass of all the asteroids. […]