Astronomers have reacted with astonishment at the massive fireball that hurtled through Earth’s atmosphere to smash into central Russia early yesterday.
The cause was an incoming asteroid, which was about the size of a double-decker bus, that broke up above the city of Chelyabinsk to cause damage to homes and factories.
The incident occurred at about 5.20am Irish time. More than 500 people were injured but there were no deaths, Russian officials said. The army quickly moved into the area, about 1,500km east of Moscow, and were keeping people away from an impact crater made by at least one piece of the asteroid.
Shock wave
The object produced a huge shock wave that shattered windows, blew in doors and knocked down part of a local factory. Dramatic video footage showed the moment the shock wave arrived. A recording from a school showed windows being blown in and people scrambling to take cover.
In a remarkable coincidence the object, properly called a meteorite, arrived on the day another asteroid was due to make an extremely close pass of Earth.
That asteroid, snappily named 2012 DA14, is about 190,000 metric tonnes of rock and was due to pass some 27,000km above Earth last night. The European Space Agency says, however, there is no connection between it and the meteorite that fell on Russia. “It was pure coincidence. They were separated by several hundred thousand miles and their trajectories were different,” said Terry Moseley of the Irish Astronomical Association. Information about the incident rapidly began to circulate among the astronomical community with experts and amateurs sharing calculations and details about what happened.
“It hit the Earth head on. It seems to have broken into at least two large fragments,” he said. Its incoming speed could have been between 40,000 and 50,000km per hour because Earth was moving towards the incoming asteroid.
That means it carried tremendous energy which allowed it to produce a powerful shockwave that would have caused most of the damage. The fragments would not have caused the main damage.
Unusual event
It is common for material in space to collide with our atmosphere, Mr Moseley said. Up to 100,000 tonnes of dust and stone rain down on us every day. It is extremely unusual, however, for an event of this size to occur more than once a decade, he said.
If the object burns up in the atmosphere without reaching the surface it is known as a meteor.
Particles the size of dust produce little or no effect, but bits of stone the size of an apple seed can produce what we call a “shooting star”, a brief streak across the night sky. Most of this material comes from comets which tend to leave a dusty trail.
Beyond Mars
Objects that reach the ground are called meteorites and these tend to be larger because they must remain intact long enough to make it through the atmosphere to land on the ground. These tend to be material that comes from the asteroid belt beyond the orbit of Mars.
Typically they are made of combinations of metal, or stone and metal, and are dense enough to hit the surface, Mr Moseley said. “This one was probably a stony one,” he said, because it fragmented. Metal-only meteorites tend to remain intact until impacting Earth.
“Scientifically this is not hugely interesting as we collect bits of meteor from all over the world already,” said Dr Simon Goodwin, reader in astrophysics from the University of Sheffield’s department of physics and astronomy.
