80 million meteors like Chelyabinsk are threat
Astronomers have identified the meteor that exploded over Russia earlier this month and say we are under threat from 80 million just like it.
The 10,000-ton asteroid, which created a nuclear-style blast above the city of Chelyabinsk, injured 1,000 people with its powerful shockwave that shattered windows and destroyed buildings.
The spectacular event was captured by countless security cameras and webcams on cars and buildings in the area. NASA has estimated the asteroid was about 17 meters (55ft) wide. The asteroid struck on the same day that 2012 DA14 skimmed past us, but that appears to be just an astonishing coincidence.
By comparing images from CCTV cameras, scientists have now been able to work out the meteor’s orbit around the Sun. Their results show that it is one of a family of rocks called the Apollo asteroids which regularly cross the Earth’s own orbit.
So far astronomers have identified more than 240 Apollo asteroids that are more than 1km in diameter , which could cause widespread devastation if they hit the Earth, but estimate there must be 2,000 of a similar size.
Smaller asteroids that cross the Earth’s path are much more common and astronomers calculate that there are around 80 million of a similar size to the one that hit Russia.
Planetary scientists Jorge Zuluaga and Ignacio Ferrin, of the University of Antioquia in Medellin, Colombia, combined data from fixed traffic cameras with precise locations and well-maintained time stamps with the location of the meteor’s impact site – a hole in the ice at Lake Chebarkul, 70km west of Chelyabinsk.
NASA video about the meteor strike.Credit: NASA
They also had to take account of other parameters such as the meteor’s height, elevation and position relative to the horizon and its ground path, or latitude and longitude.
The scientists say the Chelyabinski meteor appeared from the constellation of Pegasus near the eastern horizon where the Sun was starting to rise. It began to brighten when it was between 32 and 47 km up in the atmosphere travelling at a velocity of between 13 and 19 km per second relative to the Earth.