In 2002 a mid-sized asteroid (50-120 metres across) missed Earth by 121, 000km one-third of the distance to the moon.

ECONOMIST: Green.view: The threat from outer space | The

But one- third of it could survive, including pieces as large as a small car, and smack into the Earth as fast as 0.6 mile (1 km) a second, authorities said.

CNN: Mir demise causes international high anxiety