Astronomers know where many asteroids are, but not all.Though they may seem small and faraway, asteroids have hit the Earth many times, sometimes causing extreme destruction.It also seems clear that an asteroid will hit the Earth again in the future.Most asteroids are located in what is called the "Main Belt.This is an orbit between Mars and Jupiter
All of these asteroids are very far from the Earth and will never come close.Several hundred asteroids follow Jupiter in its orbit
These are called "Trojans"
Asteroids can also be found in the outer solar system, past orbit of Saturn.There is also a set of asteroids that orbit close to the Earth.These are called NEAs. These are also included in a group called Near-Earth Object which also includes comets.Because of their closeness, NEAs are dangerous Earth