Stickney Crater, the largest crater on the Mars’ moon Phobos, is named for Chloe Angeline Stickney Hall, mathematician and wife of astronomer Asaph Hall who discovered both the planet’s moons in 1877. At a bit more than 9 km across, Stickney is nearly half the diameter of Phobos itself. It’s so large that the impact that blasted out the crater nearly shattered the tiny moon. This enhanced-color image of Stickney was recorded by the HiRISE camera onboard the Mars Reconnaissance Orbiter at a range of about 6,000 km. Even though the moon’s gravity is less than 0.1 percent of Earth’s, streaks suggest loose material has been sliding down inside the crater walls over time.

Image Credit: NASA