APOD 2.2 Stickney Crater

Stickney Crater is the largest crater on the tiny moon, Phobos, which orbits Mars. The crater, almost 9 kilometers from side to side, is almost half the diameter of Phobos itself. The crater is named after the wife, Chloe Angeline Stickney Hall, of Asaph Hall, who discovered Mars' two moons in 1887. The impact that formed this crater most likely cam very close to shattering the minuscule Martian satellite. This picture was captured by the HiRISE camera, which is part of the Mars Reconnaissance Orbiter. The orbiter passed within 6,000 kilometers of Phobos in March of 2008, which is when this picture was taken. The image is color-enhanced, and the presence of a light blue coloration on the crater's rim could mean that the surface is newly exposed. Streaks on the crater may indicate that, over time, material has slid down the crater walls and into the crater itself. Grooves along the surface are also visible, but their origin is still under question.