Today the planets of the solar system rotate in their orbits placidly, usually oblivious to the impact of large asteroids and comets, which only collide with a low frequency, at least on a human scale. But in the beginning, the solar system was a very violent place, where the primordial planets suffered a ruthless bombardment and collided with each other countless times. Among many other things, it is believed that this type of impact was the one that created the Moon or knocked down the axis of rotation of Venus.
Therefore, understanding what happens when planets impact each other is key to understanding not only the structure of our solar system and other distant planetary systems, but also the nature of planets and exoplanets, worlds in the orbit of distant stars.
For these reasons, a team of researchers from the universities of Durham and Glasgow, in the United Kingdom, carry out simulations with the COSMA supercomputer to reveal what happened during this type of collision, paying special attention to what happens to atmospheres. His simulations, recently published in « The Astrophysical Journal», show what happens during the planet crash comparable in size to Earth, changing speeds, trajectories and other circumstances.
After carrying out 100 simulations, they have found that the most indirect collisions, that is, “glancing”, cause much less atmospheric loss than direct impacts. On the other hand, the results also show that collisions at higher speeds are capable of completely obliterate both the atmospheres and the mantle, the portion of the planets located under the crust.
The shock that created the Moon
Perhaps most interestingly, the data indicates that the impact created by the Moon, a collision that occurred between early Earth and an object the size of Mars, known as Theia, was barely wiped out 10 to 50% of our planet’s atmosphere. Therefore, their data indicates that a more direct collision could have had very damaging long-term consequences for the development of life.
“We know that planetary collisions can have a huge effect on the planets atmosphere,” said Jacob Kegerreis, co-author of the study and researcher at Durham University, in a statement. But this was the first time that we have been able to study wide variations of these violent phenomena detail”.
Thanks to this, they have found a way to predict the erosion of the atmospheres after this type of collision, which is useful to “understand both the history of Earth, as a habitable planet, and the evolution of exoplanets around other stars », In the words of Kegerreis.
After achieving these results, the researchers intend to do hundreds more simulations to check the effects of the masses and the compositions of the planets.