In 1801 Giovanni Piazzi discovered the first and largest asteroid, which he named . Today, we know that the majority of the asteroids are dark bodies, that have changed little since the solar system began. These are known as type of asteroids. The second most common type of asteroid is the type. Pieces of asteroid are found on Earth and helped astronomers to predict what the spacecraft should find when it went into orbit around it. Asteroids that cross the Earth's orbit and might hit our planet are called Asteroids.