Mars' largest moon, Phobos, is one of only two moons in our solar system that is moving toward its parent planet.
According to Science Daily, Phobos will eventually be torn apart by tidal forces, which will spread out over time and form a ring.
How much time are we talking here? Earth scientists at the University of California, Berkeley say that it will probably happen in 20 to 40 million years.
The largest pieces within the ring would eventually fall to the planet's surface, but most of the debris would likely circle the planet for millions of years.