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July 4, 2021
In the early morning of June 30, 1908, the inhabitants of Central Siberia in the area of the Podkamennaya Tunguska River observed a very unusual natural phenomenon in the sky - the flight of a fiery cosmic body (bolide) moving in a northwest direction. At 7 hours 15 minutes local time, at an altitude of about 7-10 km, an explosion of colossal power occurred.
The blast wave in a radius of up to 50 kilometers fell down the forest. The explosion was heard hundreds of kilometers away. And seismological stations across Europe recorded shock waves. For several nights after this event, unusual light phenomena were observed - from solar halos to abnormally bright nights.
Explosion area (red)
The very first version of the origin of the explosion is a huge meteorite falling to Earth. Unfortunately, no one showed scientific interest in the fall of an extraterrestrial body at that time. Therefore, the first expedition to the place of a possible fall was organized already in Soviet times in 1927. The expedition was headed by a scientist-mineralogist, student of V.I. Vernadsky, Leonid Alekseevich Kulik. He was a staunch supporter of the meteorite nature of the explosion, so he looked for traces of a meteorite falling in the area of a forest felling during five more expeditions (the last one in 1939).
However, the searches were unsuccessful. With the beginning of the Great Patriotic War, the work was stopped, and L.A. Kulik, at the age of 58, volunteered for the people's militia and died in 1942. The work was resumed only in 1949 by his student E.L. Krinov, who, having summarized all the available materials, published the first fundamental work on this topic - "Tunguska meteorite", where he developed Kulik's ideas. However, the first post-war scientific geological expedition to the site of the 1958 event completely refuted the assumption of the presence of a meteorite crater or meteorite matter near the site of the event.
Felled forest in the area of the Tunguska event
Soviet geochemist and planetary scientist K.P. Florensky in 1959 for the first time put forward a hypothesis that the Tunguska event was the result of a collision of the Earth with a comet, in which its unstable chemical compounds, in contact with atmospheric oxygen at an altitude of about 10 km, could react by producing an explosion.
Currently, there are more than a hundred hypotheses explaining the nature of the Tunguska phenomenon, but not a single one is generally accepted. This event became one of the greatest scientific mysteries of the 20th century. In 2016, by the decision of the UN, a new international date was set - Asteroid Day, which is celebrated on June 30, on the anniversary of the Tunguska event.
Source: Moscow Planetarium.
Related links:
ROSCOSMOS Press Release: https://www.roscosmos.ru/31738/
Moscow Planetarium: https://www.roscosmos.ru/tag/moskovskiy-planetariy/
Asteroid: https://www.roscosmos.ru/tag/asteroid/
Images, Text, Credits: ROSCOSMOS/Moscow Planetarium/Orbiter.ch Aerospace/Roland Berga.
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