Brown, a professor of meteor physics at the University of Western Ontario, said the energy estimate derived from infrasound records indicated that the asteroid fragment weighed approximately 10 tonnes when it entered the atmosphere. "The indicated energy is approximately one third of a kiloton of TNT," he said.

Hildebrand, a researcher at the University of Calgary, said it was likely the largest meteor to streak across the country in more than a decade.

He said that hundreds of fragments of meteorite weighing more than 1.76 ounces were likely strewn over a wide area since its speed of entry, some 14km per second, was well below the average 20km per second of most meteors.

Most meteors fall to earth at such a high speed that they burn up completely before reaching the ground.

The fireball enveloping the meteor, which Hildebrand compared to a billion-watt light bulb shining in the sky, was filmed by several people watching the spectacular event from up to 700km away.

Hildebrand said: "We are now trying to get all the transient information about the fireball before it is lost."

The National Aeronautics and Space Administration (Nasa) says that meteors reach the earth's surface because they are the right size to travel through the atmosphere.


Meteors can either disintegrate in the atmosphere if they are too small, or explode before reaching the earth's surface if they are too big.


Nasa scientists have found more than 120 impact craters and basins on earth.