DID YOU KNOW? Asteroid Day marks the anniversary of a major impact event that occurred in Siberia on 30 June 1908
As scary as an incoming asteroid may sound, it doesn’t have to mean the end of the world. It’s true space rocks sometimes collide with our planet, as happened with devastating effect 66 million years ago when a massive impact wiped out the dinosaurs. But such events are the exception rather than the rule. By astronomical standards, Earth is a very small target. Asteroids move on precisely determined orbits, so the vast majority of them simply whiz past the planet at a safe distance. Such encounters are a good thing for astronomers because they give them a chance to study asteroids at close range, and these small, rocky objects can tell us a lot about the origin and evolution of the Solar System. When the first asteroids were discovered, they were all found to lie in an ‘asteroid belt’ between the orbits of Mars and Jupiter. It’s still true today that most known asteroids are located in this region.
Asteroids can be thought of as miniature planets, a few metres to several thousand metres in size, which move on a range of orbits around the Sun in much the same way planets do. All these orbits have a similar basic shape: a kind of distorted circle called an ellipse. The point on the ellipse that’s furthest from
