The threat of space rocks smashing into Earth is bigger than previously thought, say scientists studying the terrifying meteor that exploded without warning over a Russian city last winter.

An asteroid as big as an aircraft carrier has passed by Earth in the closest encounter by such a massive space rock in more than three decades.

AN ASTEROID bigger than an aircraft carrier will dart between the Earth and moon today — the closest encounter by such a huge rock in 35 years.

For the first time ever, Nasa is setting off on a collision course with a comet, in the hope of blasting a huge hole in the celestial snowball and gazing upon the original ingredients of the solar system preserved inside.