The biggest Mars' moon, Phobos, has a number of mysterious grooves on its surface. These grooves are thought to have been formed by a process called "impact cratering." Impact cratering occurs when a small celestial body, such as an asteroid or comet, strikes the surface of a larger body, such as a planet or moon. The impact can create a large crater and also cause grooves to be formed in the surrounding area. Another hypothesis is that Phobos is a captured asteroid, so the grooves could have been formed by the collision with other space bodies before captured by Mars. However, more research is needed to confirm the exact cause of the grooves on Phobos.
