Meteor risk ‘bigger than previously thought’

Meteor risk ‘bigger than previously thought’

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

Meteors about the size of the one that streaked through the sky at 67,600 kph and burst over Chelyabinsk in February - and ones even larger and more dangerous - are probably four to five times more likely to hit the planet than scientists believed before the fireball, according to three studies published in the journals Nature and Science.

Until Chelyabinsk, the US space agency Nasa had looked only for space rocks about 30 metres wide and bigger, figuring there was little danger below that.

This meteor was only 19m across but burst with the force of about 40 Hiroshima-type atom bombs, scientists say. It released a shock wave that shattered thousands of windows and injured more than 1,600 people, and its flash was bright enough to temporarily blind 70 people and cause dozens of skin-peeling sunburns just after dawn in icy Russia.

Up until then, scientists had thought a meteor causing an airburst like the one in Russia was a once-in-150-years event, based on how many space rocks have been identified in orbit. But one of the studies now says it is likely to happen once every 30 years or so, based on how often these things are actually hitting.