Remembering the Tunguska event

The Tunguska event was an enormously powerful explosion that occurred in what is now Krasnoyarsk Krai, Russia, at about 0:14 UT on June 30 1908. The explosion is believed to have been caused by the air burst of a large meteoroid or comet fragment at an altitude of 5–10 kilometres (3–6 mi) above the Earth's surface.
The energy of the blast was nearly 15 megatons of TNT roughly equal to the United States' Castle Bravo thermonuclear bomb tested on March 1, 1954; about 1,000 times more powerful than the nuclear bomb dropped on Hiroshima, Japan (codenamed  Little Boy).