We see a streak of light. Several hundred tons of meteorites enter the Earth's atmosphere each day. Meteorites are any chunk of rock from an asteroid, a comet, or another planet that survives going through the atmosphere and actually reaches the ground. Asteroids First asteroids discovered when observers were looking for a planet between Mars and Jupiter. All the asteroids lumped together would make an object less than half the size of the Moon.
Surfaces show cratering from collisions with smaller asteroids.
It used to be believed that asteroids were once a planet that orbited between Mars and Jupiter that was destroyed by a giant collision with a large planetesimal. Now believe that the early asteroid belt was perturbed by Jupiter's gravity so that they never accreted to form a planet. Orbital resonances just like with Saturn's rings. Between the pull of the Sun's gravity and the pull of Jupiter's, the asteroids were never able to collect to form a planet. Some asteroids pass near Earth like Toutatis which has period of 4 years, and an eccentric orbit that passes close to the Earth and out to the asteroid belt.