Well, it's true that you always read articles and see movies and TV programs that talk about the destructive nature of asteroids. But I think asteroids are actually really useful!
First, all of the rocky planets were formed from smaller pieces: asteroids, essentially. So Earth wouldn't be here without asteroids. And without asteroids, Earth would probably not have a moon, since we think that the Moon was knocked off in a giant collision. Without the Moon, the evolution of life on Earth would probably have been different, since the days would be shorter, and the tides would be reduced. Also, an asteroid impact at the end of the Cretaceous was probably at least partially responsible for the extinction of many dinosaur species, which cleared the way for human evolution.
Asteroids can also help us understand the evolution of our solar system. Meteorites, which are pieces of asteroids, have allowed us to determine the age of the solar system from radioactive dating. Some asteroids are fairly pristine, and their rocks record events from the very early solar system. In addition, studying asteroids has led to some advances in our understanding of the physics of planetary (or asteroidal, or cometary) motions.
Asteroids may also be very useful in the future. For example, if we could mine them to extract metals, then we could build things in space without having to haul up a bunch of materials from Earth.
So just like other things in nature, asteroids have a good side too, and we wouldn't be here without them! And besides, there's not much we can do about all the asteroids anyway. :)
This page was last updated on July 18, 2015.