Phobos, one of the two natural satellites of Mars, is coming closer and closer to its host, leading experts to predict that the moonlet could collide with the Red Planet. Amid the new developments, a study has suggested that some pieces of the natural satellite could form a ring around the second smallest planet in the solar system.

Currently, the solar system has planets Saturn, Jupiter, Neptune and Uranus with rings. The study, published in the journal Nature Geoscience, suggested only these four planets will not be with rings in the future. The authors of the study said Mars may have a ring in 40 million years, but it could be the last time when a rocky planet will have a ring.

As per experts, a moon in orbit around its host planet always has three destinies. If the difference between a host and moonlet is right, the natural satellite stays in orbit. If a moon is beyond equilibrium, it starts gliding away from its host. If a moon is too close to its host, its orbit shrinks with time until the moon crashes into the host.

Earth’s moon is beyond the point of equilibrium, and it is drifting away from our planet 1.5 inches every year. On the other side, Phobos starts out on the too-close side, and its orbit is shrinking. Two planetary scientists at UC Berkeley, Benjamin Black and Tushar Mittal, studied spectral data from Phobos and data from other rocky objects.

“Tidal stresses exerted by Mars will break apart the weakest parts of Phobos in 20 million to 40 million years, when the moonlet is about 3,400 miles away from the planet’s surface”, the scientists said.