Russian Meteorite on Feb. 15, 2013

click here for a collection of videos that capture the Russian meteorite
According to Bill Cooke, head of NASA's Meteoroid Environment Office, "The asteroid was about 15 meters in diameter and weighed approximately 7000 metric tons. It struck Earth's atmosphere at 40,000 mph (18 km/s) and broke apart about 12 to 15 miles (20 to 25 km) above Earth's surface. The energy of the resulting explosion was in the vicinity of 300 kilotons of TNT." That is the explosive energy of 15-20 Hiroshima bombs!
Update: "The meteor was a once-in-a-century event, NASA officials said, describing it as a "tiny asteroid." The space agency revised its estimate of the meteor's size upward late Friday from 49 feet (15 meters) to 55 feet (17 meters), and its estimated mass from 7,000 tons to 10,000 tons. The space agency also increased the estimated amount of energy released in the meteor's explosion from about 300 to nearly 500 kilotons. By comparison, the nuclear bomb the United States dropped on Hiroshima in 1945 released an estimated 15 kilotons of energy. The whole event, from the meteor's atmospheric entry to its disintegration in the air above central Russia, took 32.5 seconds, NASA said." 2-16-2013 update from CNN
The link below discusses the asteroid flyby that occurred later that same day. (unrelated events!)
click here for links to sites that will stream video and pictures of the asteroid during its flyby

click here for an article discussing how Earth's gravity might cause "asteroid-quakes."