Asteroid nearly rocked our world

An asteroid measuring about 30m across has zipped past the Earth, just 60,000km from its surface and inside the moon's orbit. Australian National University astronomer Rob McNaught discovered the rock during a routine survey of asteroids passing close to the Earth. Mr McNaught said this asteroid was the closest observed approach of an object of this size or larger. ''We find about 70 near-Earth asteroids every year and this is the closest approach asteroid [of this size] we've ever found, so that was a surprise,'' he said.