Asteroids are small rocky objects that orbit the sun. Every now and then, small asteroids crash into Earth. They usually burn up in the air, like in the picture.
But what would happen if a really large asteroid was going to strike Earth? What could we do if a big one might hit our planet?
Check out these methods scientists have dreamed up to keep us safe!
1. Zap it
This may seem like a crazy idea, but scientists think one way to send an asteroid away from Earth is by surrounding it with sunlight-powered lasers. They would zap its surface so parts of it vaporise. This causes the asteroid to move in the opposite direction to Earth.
2. Crash a spacecraft into it
Unlike in the movies, an asteroid cannot be shot down in the last few minutes before it hits Earth. However, its course can be changed, for example, by launching a spacecraft to hit it with great impact. This could change its course so it is no longer a danger to us.
3. Tug it away
Another method scientists are studying is to send a special spacecraft called a "gravity tractor device". After flying it near the asteroid, the tractor could tug the asteroid off course using its own gravity. Two Nasa scientists, Ed Lu and Stan Love, say it would take about a year for the spacecraft to drag a medium-sized asteroid – weighing 60 million tonnes – away from Earth's path.
These methods are still being studied. None have yet been proven to work. They will need many years to test. This is why we must keep watching the solar system to see what may be coming our way.
