The Tunguska event (occasionally also called the Tunguska incident) was an approximately 12-megaton explosion that occurred near the Podkamennaya Tunguska River in Yeniseysk Governorate (now Krasnoyarsk Krai), Russia, on the morning of June 30, 1908. The explosion over the sparsely populated Eastern Siberian Taiga flattened an estimated 80 million trees over an area of of forest, and eyewitness reports suggest that at least three people may have died in the event. The explosion is generally attributed to a meteor air burst: the atmospheric explosion of a stony asteroid about in size. The asteroid approached from the east-southeast, and likely with a relatively high speed of about (~Ma 80). It is classified as an impact event, even though no impact crater has been found; the object is thought to have exploded at an altitude of rather than having hit the surface of the Earth. The Tunguska event is the largest impact event on Earth in recorded history, though much larger impacts have occurred in prehistoric times. An explosion of this magnitude would be capable of destroying a large metropolitan area. It has been mentioned numerous times in popular culture, and has also inspired real-world discussion of asteroid impact avoidance. Description On 30 June 1908 (N. S.) (cited in Russia as 17 June 1908, O. S., before the implementation of the Soviet calendar in 1918), at around 07:17 local time, Evenki natives and Russian settlers in the hills northwest of Lake Baikal observed a bluish light, nearly as bright as the Sun, moving across the sky and leaving a thin trail. Closer to the horizon, there was a flash producing a billowing cloud, followed by a pillar of fire that cast a red light on the landscape. The pillar split in two and faded, turning to black. About ten minutes later, there was a sound similar to artillery fire. Eyewitnesses closer to the explosion reported that the source of the sound moved from the east to the north of them. The sounds were accompanied by a shock wave that knocked people off their feet and broke windows hundreds of kilometres away. The explosion registered at seismic stations across Eurasia, and air waves from the blast were detected in Germany, Denmark, Croatia, and the United Kingdom—and as far away as Batavia, Dutch East Indies, and Washington, D.C. It is estimated that, in some places, the resulting shock wave was equivalent to an earthquake