For all the planets and an average impactor size of ∼12 km in diameter, the average impact frequency since the Late Heavy Bombardment is one every ∼1.9 Gyr for the Earth and 2.1 Gyr for Venus. For smaller bodies (e.g.,>1 km), the impact frequency is one every 14.4 Myr for the Earth, 13.1 Myr for Venus and, 46.3 for Mars, in the recent solar system.
Astrophysicists Mattia Galiazzo and Rudolf Dvorak of the University of Vienna, in collaboration with Elizabeth A. Silber of Brown University, have calculated the number of close encounters and impacts of Centaurs with terrestrial planets (Mars, Earth, Venus, and Mercury), after the so-called Late Heavy Bombardment.
The Late Heavy Bombardment is thought to have occurred some 3,800 million years ago. Researchers also calculated the possible sizes of craters after a collision between Centaurs with Earth and other terrestrial planets in our solar system.
Centaurs originate mainly from trans-Neptunian objects and are among the sources of near-Earth objects.
This makes them objects of extreme interest for experts. Astrophysicists say that it is crucial to understand their orbital evolution, which in some cases can lead to a collision with the solar system’s inner planets and produce catastrophic events.
Astrophysicists studied the orbital evolution of centaurs towards the inner solar system and calculated the number of close encounters and impacts with terrestrial planets after the so-called Late Heavy Bombardment, assuming a stable population of centaurs is out there,
“We also estimate the possible crater sizes. Centaurs can become also active comets, because of the presence of water on a good number of them, thus we also compute the approximate amount of water released to the Earth, which is comparable to the amount of water present on the Adriatic Sea, now. We also found subregions of the Centaurs where the possible impactors originate from”, explains Mattia Galiazzo.
Crater sizes could extend up to hundreds of kilometers in diameter; however, given the known population of centaurs, most of the craters would be less than 10 km.
For all planets and an average impactor size of 12 km in diameter, the researchers estimate on average two impacts from the Late Heavy Bombardment for Earth and between one and two for Venus.
Experts explain that this cosmic “bombardment” is less intense (of at least a tenth part) than the impacts of asteroids that originate between Mars and Jupiter.
However, centaurs are on average much faster and more massive.
For smaller centaurs (for example, with a diameter of more than 1 km), the impact frequency is much higher, approximately one every 14 million years for Earth, 13 million years for Venus and 46 million for Mars.
Interestingly, scientists have discovered that half of the centaurs can enter the region of terrestrial planets and about 7 percent of them interact with them.
Scientists believe that Centaurs could be the cause of past catastrophic events on Earth.
These results provide an important contribution to the analysis of catastrophic events of extraterrestrial origin, which also occur on planets such as Mars and Venus.
“Our work also provides the framework to understand better past events, and how they could have altered life on Earth and other planets,” concludes Galiazzo.
The report was published in Monthly Notices of the Royal Astronomical Society.
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