There is also a planet called Gliese-581g, discovered in September 2010, which is thought to be even more like Earth than Kepler-22b in terms of its suitability for plants and animals.
During this violent time, much of the debris would have resembled comets - dirty snowballs thought to be mostly slushy water surrounding a rocky core - slamming into Earth at velocities greater than 25 km per second (16 miles per second).
Aussies seemed to warm to his down-to-earth style and he was thought to have had such a good time that it fuelled speculation that he might end up honeymooning in Australia.