In 2013, a meteor exploded in the sky over Russia's Ural Mountains. It produced a shock wave so intense that about 1,000 people were reported injured, mostly by flying glass fragments. To view the meteor streaking across the sky, many people were at their windows when the sonic boom shattered the glass panes. The meteor was estimated to ;be 2 meters in diameter, with a mass of about 10 tons. It entered the Earth's atmosphere at a hypersonic speed of at least 33,000 mph when it was viewed by residents of Chelyabinsk (a city of 1 million about 930 miles east of Moscow) at about 9:20 am local time, just after sunrise. They saw a thick, white contrail and an intense flash of light ending with a loud thundering sound as the shattering of the meteor blew apart with several kilotons of energy (equivalent to an atomic bomb)