[Quote]:

The dramatic fireball that exploded over Russia today (Feb. 15) was apparently the biggest such blast in more than a century, scientists say.

The object that caused the Russian fireball, which damaged hundreds of buildings and wounded perhaps 1,000 people in the Chelyabinsk region, was originally probably about 50 feet (15 meters) in diameter and weighed roughly 7,000 tons, said Peter Brown, director of the Center for Planetary Science and Exploration at the University of Western Ontario in Canada.

From multiple sensors using multiple technologies, a best initial estimate of the total energy of the event is about 300 kilotons of TNT-equivalent, Brown said, though he stressed that the number could change as scientists learn more.