Mars's Moon Phobos Will Crash Into Mars or Break Apart

Mars has two small moons, Phobos and Deimos, which NASA says may be captured asteroids. Phobos, the innermost and larger of the two, is heavily cratered and has deep grooves on its surface. It also has a limited future. NASA states that Phobos is slowly moving towards Mars and will crash into the planet or break apart in about 50 million years. Mars might gain something in the process. According to NASA, if Phobos breaks apart, it could create a dusty ring around the Red Planet. The other moon is quieter. Deimos is about half as big as Phobos and orbits two and a half times farther from Mars. Its craters are often filled with loose dirt, which makes it look smoother than pockmarked Phobos. NASA also notes that Phobos is the innermost of the two moons, circling closer to Mars than Deimos does.