Phobos

Phobos is one of the two small moons orbiting Mars, the fourth planet from the Sun. It is irregularly shaped and much smaller than Earth's moon, measuring about 22 kilometers across. Phobos orbits very close to Mars, completing a revolution roughly every 7.7 hours. It is heavily cratered, with a large impact scar called Stickney. Due to its proximity, Phobos is gradually spiraling toward Mars and may eventually break apart or crash into the planet. Scientists are interested in Phobos for insights into planetary formation, the history of Mars, and potential future exploration or use as a space station or mining site.