At 03:20 GMT on 15 February, a natural object entered the atmosphere and disintegrated in the skies over Chelyabinsk, Russia.
Extensive video records indicate a northeast to southwest path at a shallow angle of 20° above the horizontal. The entry speed is estimated at around 18 km/s — more than 64 000 km/h.
According to calculations by Peter Brown at the University of Western Ontario, Canada, drawing on extremely low-frequency sound waves detected by a global network, the object is estimated to have been about 17 m across with a mass of 7000–10 000 tons when it hit atmosphere.
It exploded with a force of nearly 500 kilotons of TNT — some 30 times the energy released by the Hiroshima atomic bomb — around 15–20 km above the ground.
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