Asteroid Day (also known as International Asteroid Day) is an annual global event which is held on the anniversary of the Tunguska event in 1908The Tunguska event (occasionally also called the Tunguska incident) was a ~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 2,150 km2 (830 sq mi) 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 meteoroid about 50–60 metres (160–200 feet) in size. The meteoroid approached from the east-southeast, and likely with a relatively high speed of about 27 km/s (60,000 mph) (~Ma 80). It is classified as an impact event, even though no impact crater has been found; the object is thought to have disintegrated at an altitude of 5 to 10 kilometres (3 to 6 miles) rather than to have hit the surface of the Earth.
