A huge mass of rock hurtling in from space could really make a mess of your weekend plans. So it's comforting to know that the world's astronomers are out there keeping an eye for any potential earth-grazers. See their discoveries over the past 30 years in this beautifully-designed animation:
Earth crossers are in red; earth approachers are in yellow; other asteroids are in green.
I love the way that the Earth with all its telescopes appears almost as a lighthouse beacon, peering into the murky depths of space.