Dozens of asteroids approach Earth every year to a distance less than the distance that separates it from the Moon, yet they rarely collide with our planet.
Reveal study New scientific research suggests that the secret behind this phenomenon lies in the Earth and similar planets having a built-in defense system that relies on the force of gravity, which it uses to repel the threat of intrusive asteroids.
The simulation results conducted by the researchers in the study showed that gravitational forces known as tidal forces can tear asteroids into pieces as they approach Earth.
Does the Earth experience strong tidal forces?
It is known that celestial bodies with huge masses, such as planets and moons, exert great gravitational forces on objects close to them, causing forces similar to those that cause tides on Earth caused by the Moon. These forces can be so strong that objects are subjected to tidal disturbances and end up being torn apart.
In 1994, amateur astronomers witnessed a first-hand occurrence of this dramatic destructive force when pieces of Comet Shoemaker-Levy 9, torn apart by tidal forces during a two-year approach to the gas giant, collided on Jupiter. But for decades, astronomers were unable to Evidence was found that tidal forces resulting from the Earth and rocky planets such as Mars, Venus, and Mercury similarly affected asteroids or comets that approached them.
In 2016, planetary scientist at Luleå University of Technology in Sweden and lead author of the new study, Mikael Granvik, along with other researchers, created a simulation model that calculates the trajectories of asteroids of different sizes to determine their number at different distances from the Sun and study their movement.
And according to a report Published on the Live Science website, the researchers compared the model’s simulation results with data obtained over a period of seven years by NASA’s astronomical observatory in Arizona to track large and small asteroids observed at distances close to the orbits of Earth and Venus around the sun.
The results showed that small asteroids are nothing but fragments that previously separated from larger asteroids due to the forces of duration and tidal action on Earth and Venus.
Forces that turn asteroids into fragments
To test this idea, Granvik and co-author Kevin Walsh, a researcher at the Southwest Research Institute in Colorado, looked at a simulated scenario in which large asteroids approaching rocky planets lose between 50 and 90 percent of their mass, generating streams of fragments.
The process of comparing the results of this scenario with observational data revealed the accuracy of the model in explaining the movement of small asteroids, indicating that they arose due to tidal disturbances. It also showed that these asteroids emerging from fragments remain for a very long time, lasting an average of 9 million years, before they collide with the sun or planets or escape outside the solar system.
The researchers described the simulation results in The new study It was published in The Astrophysical Journal Letters and is available in the preprint database arXiv, which allows scientific papers to be made public before they are published in the journal.
According to the study’s authors, tidal disturbances caused by Earth can help combat asteroids, but at the same time they cause more near-Earth objects to form that could hit the planet. However, there is no need to panic, because these fragments do not exceed one kilometer in diameter, and they do not pose a threat of extinction, Granvik said.
