The Russian Meteorite and the Asteroid:Complete Details

An explosion that had the force of a nuclear weapon occurred over Chelyabinsk,Russia Friday morning,injuring more than 1,000 people,as a 10 ton meteorite blew up in the earth's atmosphere.The space rock,a chunk of a comet or asteroid,was about 49 feet wide and traveling at a speed of at least 33,000 miles an hour when it disintegrated,resulting in a sun-like fireball and destructive shock waves.
The meteorite broke into pieces 18-32 miles above the ground over the Ural Mountains city of about a million people about 930 miles east of Moscow.Some of the fragments fell in a reservoir outside the town of Cherbakul,leaving a 26 foot wide crater in the ice.
Over 4,000 buildings were damaged in the Chelyabinsk area,including 6 hospitals and 12 schools.Most of the damage was in the form of shattered windows from the sonic boom the explosion created,but the roof of a zinc factory partially collapsed as well.School had just opened when the meteorite hit at 9:20 am local time.Flying glass injured 258 students.
Around 1100 people received medical treatment,and 48 of them were hospitalised.The broken windows will expose area residents to the region's bitter cold,which dips below zero Fahrenheit at night.
Chelyabinsk is 3,000 miles west of Tunguska,Siberia,site of a 1908 cataclysm caused by a 10 megaton explosion of a space rock.That blast flattened some 80 million trees and was the largest recorded explosion of a space object.
NASA scientist Jim Green said that fireballs happen once a day or so,but go unseen because they are over the ocean or remote areas.An event of the magnitude of  the Chelyabinsk blast happens about once every 10 years.
In a separate and unrelated incident Friday afternoon,asteroid D-14 made a near-earth visit at 2:25 pm EST,coming within the geosynchronous orbit of 22,236 miles.That means it was closer to the earth than weather satellites.The asteroid is about 150 feet wide,or three times as large as the Chelyabinsk object.
Scientists said they would study the asteroid with radar to determine how fast it was spinning and perhaps its composition.It was invisible to the naked eye.