Tunguska event

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Coordinates: 60°55′N 101°57′E

Tunguska event
Location of the event in Siberia (modern map)
Event	Explosion in forest area (10–15 Mtons TNT)
Time	30 June 1908
Place	Podkamennaya Tunguska River in Siberia, Russian Empire
Effects	Flattening 2,000 km2 (770 sq mi) of forest; seen by glowing sunsets
Damage	Mostly material damages to trees
Cause	Probable airburst of small asteroid or comet

The Tunguska event was an enormously powerful explosion that occurred near the Podkamennaya Tunguska River in what is now Krasnoyarsk Krai, Russia, at about 07:14 KRAT (00:14 UT) on June 30, 1908.^[1][2][3] The explosion, having the epicentre (60.886°N, 101.894°E), is believed to have been caused by the air burst of a small asteroid or comet at an altitude of 5–10 kilometres (3–6 mi) above Earth's surface. Different studies have yielded widely varying estimates of the object's size, on the order of 60 m (200 ft) to 190 m (620 ft).^[4] It is the largest impact event on or near Earth in recorded history.^[5]
The number of scholarly publications on the problem of the Tunguska explosion since 1908 may be estimated at about 1,000 (mainly in Russian). Many scientists have participated in Tunguska studies, the best-known of them being Leonid Kulik, Yevgeny Krinov, Kirill Florensky, Nikolai Vladimirovich Vasiliev, and Wilhelm Fast.^[6] In 2013, a team of researchers led by Victor Kvasnytsya of the National Academy of Sciences of Ukraine published analysis results of micro-samples from a peat bog near the blast epicenter showing fragments possibly of meteoric origin.^[7][8]
Although the asteroid or comet appears to have burst in the air rather than hitting the surface, this event still is referred to as an impact. Estimates of the energy of the blast range from 3 to as high as 30 megatons of TNT (13–130 PJ),^[9][10] with 10–15 megatons of TNT (42–63 PJ) the most likely^[10]—roughly equal to the United States' Castle Bravo thermonuclear bomb tested on March 1, 1954; about 1,000 times more powerful than the atomic bomb dropped on Hiroshima, Japan; and about two-fifths the power of the later Soviet Union's own Tsar Bomba (the largest nuclear weapon ever detonated).^[11]
The Tunguska explosion knocked down an estimated 80 million trees over an area covering 2,150 square kilometres (830 sq mi). It is estimated that the shock wave from the blast would have measured 5.0 on the Richter scale. An explosion of this magnitude is capable of destroying a large metropolitan area.^[12] This possibility has helped to spark discussion of asteroid deflection strategies.