The European Space Agency has released an assessment on the recent asteroid impact over Chelyabinsk.
Quotes:
The entry speed is estimated at around 18 km/s – more than 64 000 km/h.
... the object is estimated to have been about 17 m across with a mass of 7000–10 000 tonnes 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.
It seems that the Mayans were only a tiny bit off in their calculations.
