790 thousand years ago, the collision of a kilometer-long asteroid with the Earth caused an explosion with a power of a million megatons of TNT.
A group of German geophysicists and planetary scientists found that about 790 thousand years ago, a series of asteroid impacts of enormous force hit the Earth. Scientists came to this conclusion based on the study of various groups of tektites - glass samples arising from the earth rocks melted by the impact of a meteorite. In TNT equivalent, the aggregate power of explosions from collisions is 150 times higher than the power of the nuclear arsenal of all countries of the Earth, which today is close to 7 thousand megatons. The results of the work were published in the journal Geochimica et Cosmochimica Acta.
Using the argon-argon method, scientists have dated tektite samples from Australia, Southeast Asia and Canada. It turned out that most of them are of the same age. Most often, it ranged from 787 to 793 thousand years. This means that, probably, their formation is associated with the same event - the fall of a large asteroid or comet. Given the vast area over which the samples of such glass were scattered, they must have resulted from the fall of a rather large body, about a kilometer in diameter. According to the researchers, the power of the explosion upon collision with it should have been about a million megatons.
Also, scientists believe that the explosion was not one. Argon-argon analysis of a number of tektites from Central America, carried out by the same scientific group, showed that most of the samples from this region are 777 thousand years old (plus or minus 16 thousand years). Consequently, they are practically "contemporaries" of Australian, Asian and Canadian models and, therefore, the events that gave rise to them could be simultaneous. It cannot be ruled out that more than one body fell to the Earth at that moment, because a number of asteroids have satellites gravitationally associated with them.
According to geophysicists, the consequences of the fall of such a body or bodies must have been catastrophic. A powerful tsunami took place in the Pacific Ocean basin, presumably penetrating tens of kilometers into the interior of the continents. Australia appears to have had extensive fires, and the mass of material released into the atmosphere has reduced the amount of sunlight reaching the planet's surface, causing the temperature on it to drop significantly. Oddly enough, no significant extinctions were recorded at this moment, which, most likely, indicates the stability of ecosystems of that period.
According to modern concepts, tektites are formed by 98 percent of terrestrial rocks and 1-2 percent of cosmic dust. When a celestial body is large enough to at least partially reach the surface, a large amount of rock, heated to several thousand degrees, is thrown out of the crater at the point of its fall. Part of it is blown away by an explosion above 100 kilometers, where the atmosphere is practically absent. Since the velocity of the bulk of such molten droplets is lower than the first and second cosmic ones, they quickly fall down.
During rapid heating and cooling, silicon dioxide, which constitutes the bulk of tektites by weight, turns into dark green glass (sometimes dark brown or light green), the pieces of which, as a rule, do not exceed several centimeters in size. Smaller similar objects were formed during the most powerful ground-based nuclear tests.
Earlier, using tektites, it was possible to determine a number of parameters of the Chicxulub asteroid, which fell to Earth 65 million years ago. It is assumed that its energy was equal to about 100 million megatons, that is, 15 thousand times higher than the total power of all nuclear weapons existing on Earth.
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