The probability of one of these Near-Earth Objects hitting Earth over the next hundred years is virtually negligible. However, scientists are concerned, because at present, there are about 900 asteroids circulating our solar system. If an asteroid the size of Eros fell on Earth in the middle of the Atlantic, it would have catastrophic effects.
But there are also other hazards from space. Thousands of nuts, bolts, and other debris from space missions form an orbiting garbage dump. Some of these bits and pieces fall back into Earth's atmosphere and behave just like any other meteor, lighting up the sky like a "falling star.