A huge asteroid, up to five times larger than the rock thought to have wiped out the dinosaurs, crashed into Earth more than 3 billion years ago, say researchers Dr Norman Sleep and Dr Donald Lowe from Stanford University. A graphical representation of the size of the dinosaur-killing Chicxulub asteroid, and the crater it created, compared to an asteroid thought to have hit the Earth 3.26 billion years ago and the size of the crater it may have generated....
