The Chelyabinsk meteor exploded over a rural area of Russia on 15th February 2013. As well as causing significant damage - although amazingly resulting in no deaths - it was one of the first asteroids to be caught on video, with images of the incident going viral on YouTube and other video sharing sites. New studies have indicated that said videos have provided scientists with fresh insights into what can happen when asteroids enter Earth's atmosphere - and that the risk of similar incidents might be much higher than previously estimated.
In the studies published by Science and Nature journals, it is revealed that the Russian asteroid - weighing 12,000–13,000 metric tonnes - was twice as heavy as previously thought. It entered Earth's atmosphere at around 50 times the speed of sound, and exploded at an altitude of 27 km. Several rock fragments hit the ground, with the largest fragment - weighing 600 kilograms - recently recovered from a lake. JiÅ™í BoroviÄka explains "luckily, most of the kinetic energy was absorbed by the atmosphere. A more solid rock that might have blasted closer to the ground would have caused considerably more damage."
The researchers go on to warn that the damage could have been much more significant had the explosion occurred in a more densely populated area, especially if the explosion itself took place at a lower altitude. It had been estimated that meteor impacts of this scale on average once every 150 years, but the new data suggests that figure could be "an order of magnitude" larger.
The reason behind the revised estimate - indicating that such an impact could take place every few decades, on average - is that the Chelyabinsk meteor has helped scientists re-evaluate the risks posed by smaller asteroids. Although most of the solar system's large and potentially apocalyptic asteroids (1 km or more) are actively monitored, there are millions of largely unknown smaller rocks that could cause serious damage if they enter the atmosphere.
Luckily, more advanced asteroid monitoring and warning systems are being developed, while scientists remain confident that none of the larger asteroids will come dangerously close to Earth for at least the next few centuries.
Ukranian astronomers recently identified 2013 TV135: a 410-meter wide asteroid with a 1 in 63,000 chance of hitting Earth in August 2032.
