Life on Earth exists today due to the fact that there are no large "super-Earths" in the solar system, whose attraction will "target" the asteroids approaching them to other planets, says an article posted on the arXiv.org electronic library.
“Asteroids, as a rule, are a great threat to all life forms - to verify this statement, it is enough to look at the dinosaurs. On the other hand, they are extremely important for its origin, since they can be one of the main sources of water and “building blocks of life” for the Earth and other planets where there is life. - says Rebecca Martin from the University of Nevada in Las Vegas (USA).
The Earth is currently the only planet we know of with life on its surface. Over the past ten years, astronomers have discovered about two thousand planets, many of which are similar to Earth in size and physical properties, but most likely devoid of life.
These discoveries made scientists think about what distinguishes our planet from all its "cousins", and what features of its birth and evolution could make it suitable for the emergence of the first living things and their survival over the past 3.5-4 billion years. Martin and her colleagues discovered one similar feature of the solar system that could explain the absence of life on other planets.
Observing the birth of the Earth and other planets in a virtual version of the solar system, scientists changed its architecture, adding or removing planets from it. When planetary scientists "inserted" a large "super-Earth" into it, placing it in the orbit of the hypothetical Phaeton, a non-existent planet between the orbits of Mars and Jupiter, and in the gap between Venus and Earth, something unusual happened.
It turned out that the appearance of a large rocky planet, even at sufficiently large distances from the Earth, led to the fact that our planet began to be bombarded by a huge number of asteroids for a very long time after its formation. On average, the appearance of such a planet between Earth and Venus increased the number of asteroids that fell to Earth by 1.5-3 times.
The increase in collisions, as scientists explain, will occur because the gravity of the "super-Earth" will orchestrate the movement of asteroids that live in the zone between the orbits of Mars and Saturn and periodically approach the Earth. The presence of a large planet in the inner part of the solar system would noticeably "stretch" their orbits, forcing them to come closer to the Earth more often and periodically fall on its surface.
Fortunately, there is no such planet in the solar system, thanks to which the Earth avoided the fall of a large number of large asteroids after the birth of life on its surface. On the other hand, almost all exoplanet systems known to us, where there are potential "Earth twins", have such planets, which may partially explain why scientists have not yet found traces of extraterrestrial life.
Promotional video:
Interestingly, the presence of such an object beyond the Earth's orbit, on the contrary, would reduce the frequency of collisions of asteroids with our planet. Scientists believe that this would also negatively affect the chances of the birth of the Earth, since then much less water and "bricks" of life would fall on its surface in the first stages of the existence of the solar system.