Mars closest moon, Phobos, is about to crash into the planet's atmosphere, creating a ring around it in the process. Phobos currently orbits Mars at around 3,700 miles above the planet's surface. It's currently on its way inward - eventually it'll start to break apart. The sad news is, we won't be able to see this crash happen. The good news is, we won't be around to see any potential ill effects. This ring-making will take place in between 20 to 40 million years from now.