Earth’s gravity could tear apart space rocks, reducing asteroid danger

Each year, dozens of asteroids come closer to Earth than the Moon, but collisions with asteroids are extremely rare. New research suggests that our planet has a kind of built-in defense system, and its powerful gravity actively acts against asteroid invaders. Because of their enormous mass, planets and their moons exert significant gravitational effects on nearby objects. An important factor is the tidal force caused by differences in gravity. These forces, known to astronomers’ research because they affect the Earth’s tides, are so powerful that they can cause objects to collapse, so-called tidal disruption. In 1994, space observers discovered the dramatic effects of tidal disruption when debris from comet Shoemaker-Levy 9, torn apart by Jupiter’s tidal forces after passing near Jupiter two years earlier, collided with the gas giant. I witnessed an example. However, astronomers for a long time could not confirm that the destruction of the Earth and other terrestrial planets could also lead to the destruction of passing asteroids and comets. Mikael Granvik of the Swedish Institute of Technology in Luleå has been searching for gravity-separated near-Earth asteroids (NEAs) for years. “Ten years ago, we looked for NEA families that might have formed due to tidal influences, but we couldn’t find them,” Grunwick said of his own experience. Subsequent research explained why. The resulting fragments “very quickly fade into the background,” making it impossible to identify specific families. However, the search for the gravity-destroyed asteroid was put on hold until Grunwick came to a new conclusion. In 2016, we helped develop a model that can calculate the orbits of asteroids of different sizes and determine the number of asteroids at different distances from the sun.