A METEOR that exploded over Russia in February was 20 metres in diameter and caused a blast equivalent to 600,000 tons of TNT, according to scientists who are studying the event.
The space rock blew apart 18.5 miles above the city of Chelyabinsk, briefly outshining the sun and inflicting severe burns on people watching.
It was the biggest object to hit the Earth since the Tunguska event of 1908, when an exploding comet or asteroid destroyed 2,000 sq km of Siberian forest.
Professor Qing-Zhu Yin, from the department of Earth and planetary sciences at the University of California at Davis, described the massive meteor strike as a frightening "wake-up call".
He said: "If humanity does not want to go the way of the dinosaurs, we need to study an event like this in detail."