On Feb. 15 at 3:20 Coordinated Universal Time a meteorite exploded over the city of Chelyabinsk in central Russia. Travelling at a speed of around 18 km/sec (40,000 mph) when it broke the Earth’s atmosphere, the meteor created a shock wave that damaged several buildings and windows within Russia’s Ural Mountain region. The trail left behind by the meteor could be seen as far as 200 km away.
The descent of this meteor occurred 16 hours before an asteroid, labelled “2012 DA14,” was expected to pass by Earth. Although it is interesting that these two astronomic phenomena occurred on Feb. 15, the Russian meteor and the asteroid flyby were independent events.
NASA reported that “the trajectory of the Russia meteor was significantly different than the trajectory of the asteroid 2012 DA14, making it a completely unrelated object.”
News of the Russian meteor spread quickly, as videos, several from dashboard cameras of cars in Russia, went viral over the internet. The videos showed the meteor shine brightly and pierce across the sky at a fast rate. NASA used many of these videos to determine that the meteor was moving from north to south. This was in contradiction with the trajectory of the DA14 asteroid, which was moving from south to north when it passed by Earth.
The DA14 asteroid flyover was the closest an object of its size has approached Earth in recorded history, coming within 27,700 km above the Earth’s surface – closer than several of the world’s orbiting satellites and around 1/13th of the distance from the Earth to the Moon. With an estimated diameter of 45 metres across and a mass of 130,000 metric tons, the 2012 DA14 asteroid was much larger than the Russian meteor, which was estimated to be 17 metres across and 10 metric tons.
While the 2012 DA14 asteroid was expected to fly by planet Earth on the 15th, space experts did not anticipate the meteor over Russia. However, NASA correctly predicted that the DA14 asteroid was never going to impact Earth.
Although the Russian meteor was only one-third the diameter of the DA14 asteroid, infrasound data from around the world has led to an estimate of nearly 500 kilotons of energy liberated by the meteor’s explosion. By comparison, the shock wave (or sonic boom) and associated energy released by the atomic bomb that was dropped on Hiroshima in 1945 was 15-16 kilotons.
The damage caused by the impact wave following the meteor explosion included 200,000 square metres of shattered window glass in Chelyabinsk. Among the many homes and businesses damaged was the Chelyabinsk Zinc Plant, which received the worst hit, with some of its walls having collapsed after the meteor’s energy release. The impact left 1,491 people injured, including 311 children; however, no deaths were reported.
Russia is not unaccustomed to objects from space landing in its territory. A meteor shower struck the village of Tsaryov in southern Russia in 1922 with 1.6 tons of meteor fragments.
The recent meteor seen near Chelyabinsk has been compared to a 1908 event in Tunguska, where a meteor exploded above the Podkamennaya Tunguska River in Siberia (what is now Krasnoyarsk Krai, Russia) and flattened around 2,200 square kilometres of forest. It remains the largest natural explosion recorded in recent history.
The two serendipitous though unconnected astronomic events occurring on the same day has sparked a conversation in the space and lay community surrounding the technologies humanity currently employs to track incoming space objects. While one was a predicted and benign passerby, the other—the meteor—was unanticipated and unwelcome – a quaint reminder of how utterly vulnerable we are to the capricious workings of the cosmos.
