Every so often scientists announce that a large space rock or asteroid will pass within a couple of hundred thousand kilometres of Earth. The tabloid press proclaim a near miss and that we were lucky to dodge Armageddon. Headline grabbing stuff it may be, but the truth of the matter is, that it is only a matter of time until the Earth experiences an impact event when one of these asteroids makes it through our atmosphere and explodes with tremendous force creating significant damage.
This happened 65 million of years ago when a 10 km rock smashed into the Earth, throwing up a huge cloud of dust and debris that darkened the planet. This resulted in the extinction of the dinosaurs and three quarters of the species alive at the time. Good news for us however, as it eventually led to humans evolving.
In 1908, a few kilometres above a remote area of Siberia known as Tunguska, an asteroid somewhere between 50 and 200 metres across, exploded and flattened some 2000 square kilometres of forest. Luckily no one was killed, as the explosion occurred miles from any civilisation. It would have been a different scenario had the explosion occurred above a large urban development.
In February 2013, a 20 metre ball of rock exploded 30 km above Chelyabinsk in Russia. The resulting shockwave created some minor structural damage and blew out many windows leading to 1500 injuries. This event was record by numerous sources, including many car dash cameras. Impacts of space rocks happen on a daily basis and many thousands of space rocks make it onto our planet every year, most of them small and insignificant. A shooting star or meteor is a small piece of space rock burning up as it enters our atmosphere.
According to NASA, once a year an object the size of a car hits Earth’s atmosphere and burns up creating an impressive fireball. Every 2000 years or so an object the size of a football field comes knocking and causes major damage. Finally, every few million years or so, an object large enough to threaten our civilisation comes along. NASA have a monitoring programme and track over 15000 near Earth asteroids. We could probably deal with a potential impactor given enough time, but it is the ones that sneak up on us that are the worry. So until we have a rapid response plan, ready to go at a moment’s notice, here’s hoping that the only meteors we see are shooting stars as they light up our night sky.