On 15 February 2013, an asteroid about 50 m in diameter passed within 27,700 km of the Earth. Although there was almost no chance of it colliding with our planet, it did come a little too close for comfort, passing beneath the orbit of our geostationary satellites. An asteroid of approximately the same size destroyed 2000 km2 of Siberian forest in 1908.
The Asteriod Belt between Mars and Jupiter contains millions of these rocky fragments, the biggest among them measuring one-quarter the size of the Moon. One asteroid, the 300-m Apophis, will pass relatively close to Earth a number of times in the coming decades, including in 2029.
In an interview he gave A World of Science in 2009, Italian astronomer Giovanni Valsecchi explains that both asteroids and comets are being tracked by astronomers today. However, there is no official channel for warning governments of an impending impact. Among the ideas put forward to prevent an asteroid impact, some have suggested that it could be rammed by a missile or spacecraft, or even nuked, if deflection were not an option! Any one of these technological solutions would be extremely costly and necessitate a long-term investment. Given the low probability of an asteroid hitting the Earth this century, this begs the question as to whether governments consider preparations a priority.