We all know that Mars has two moons that are orbiting the planet, Phobos and Deimos. Up until now, scientists believed they had to deal with asteroids, but that was not the case. According to the orbit of Deimos, that would not be possible anyway.
It seems that Deimos is tilted to the equator of Mars with two degrees. This difference is so small that they didn’t even take it into consideration: “The fact that Deimos’ orbit is not exactly in plane with Mars’ equator was considered unimportant, and nobody cared to try to explain it. But once we had a big new idea and we looked at it with new eyes, Deimos’ orbital tilt revealed its big secret.”, stated Matija Cuk, the lead author of the study.
This is how the ring is formed
They found out more with the help of the motions of Phobos, that orbits closer to the surface of Mars, and that is slowly spiraling into the planet. It seems that, eventually, Phobos will get closer to Mars, and the gravity of the planet will pull the moon into many pieces, forming a ring.
However, this might not be a one-off event. After the moon is pulled apart, it will form another moon. This has happened before. This process might explain why the orbital tilt happened to Deimos.
According to the scientists, a newborn moon would move away from the ring and Mars would go in the opposite direction from the inward spiral that Phobos does, because of the gravitational interactions with the planet.
This process outside the ring might meet the so–called orbital resonance, in which the orbital period of Deimos is three times that of Phobos. “We can tell that only an outward-moving moon could have strongly affected Deimos, which means that Mars must have had a ring pushing the inner moon outward.”