The red planet Mars’ moons Phobos and Deimos are likely formed from debris created when a large asteroid orbited dangerously close to it, as computer simulations suggest.
According to this new model, Phobos and Deimos were formed as a result of debris from a large asteroid that orbited too close to Mars and exceeded its orbital limit. Space.com.
It is also worth noting that the Roche limit was the distance at which the gravitational tidal forces from the planet became too great and tore the asteroid apart.
“It’s exciting to find a new option for making Phobos and Deimos — the only moons in our solar system that orbit a rocky planet other than Earth,” said Jacob Kegres of the NASA Ames Research Center.
Martian moons are not easy to explain. Both are small — Phobos is 16 miles (26 km) at its widest point, while Demos is only 10 miles (16 km) — and lumpy. This makes them look like captured asteroids.
However, objects captured in orbit around their new parent planet have long, inclined, and sometimes retrograde paths.
Neptune’s moon Triton, or Saturn’s moon Phoebe are good examples.
Additionally, Phobos and Deimos have neat circular orbits along the equatorial plane of Mars. This makes it more likely that they formed in orbit around Mars.