The large asteroids collide with the Earth every two billion years.
In the years of youth of the Solar system for a relatively short transitional phase there were frequent collisions with asteroids, some of which belonged to large asteroids.
The Vienna astronomers have calculated the probability of collision with small planets of Earth, Mars and Venus. As they report in an article published in the scientific journal Monthly Notices of the Royal Astronomical Society, major centaurs – the so-called special class of asteroids fall to the Earth, Mars and Venus with the statistical frequency of two billion years.
Centaurs are smaller, as follows from the results of this work fall into our planet more often – every 15 million years. Most asteroids move around the Sun, located between Mars and Jupiter and form the so-called main asteroid belt.
But these celestial bodies are present between Jupiter and Neptune, and these asteroids are composed mostly of ice, called centaurs. But because of the significantly large volumes of this belt, it is full of such celestial bodies is much less tight.
And since they are removed from each other much more, they face not as often as the asteroids in the main belt. Therefore, there are much larger objects, the diameter of which can reach tens and even hundreds of kilometers.
Because they fly at a considerable distance, we are aware of only the largest bright objects, says Rudolf Dvorak from the Institute of astrophysics of the University of Vienna. Their highly elongated elliptical orbit around the Sun may cross the orbits of terrestrial planets, i.e. mercury, Venus, Earth and Mars. A collision with them can have disastrous and even fatal consequences.
Dvorak, along with his Viennese colleague Mattia, Galiazzo, as well as colleagues from the United States conducted a study of long-term development of the orbits of centaurs and counted the number of possible close passes and collisions with the Earth, Mars and Venus. While scientists have focused on the phase after the so-called Late Heavy Bombardment (“Late heavy bombardment”), phases of heavy clashes with partly very large asteroids, which ended approximately 3.8 billion years ago.
“The statistical frequency of contact with the Earth, Mars or Venus is for large centaurs about once in two billion years for smaller asteroids with sizes of about one kilometer from this zone – approximately every 15 million years,“ says Dvorak.
Therefore most craters that occur at such events does not exceed the size of ten kilometers. Read also: the Fall of an asteroid to Earth will destroy all life “So the clash with the centaur is about ten times less likely than a collision with an asteroid of the main belt,“ explains Dr. Galiazzo.
However, this calculation is very important, since “the Centauri are much larger objects and collision with the terrestrial planets is due to their highly elliptical orbits at greater speeds,“ says Dvorak.
The researchers show that over the last four billion years, the centaurs could be the cause of at least two mass extinctions on Earth.
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