NASA’s Astronomy Picture of the Day for Oct. 9, 2026 focuses on Stickney Crater, the largest crater on Phobos. NASA says the crater is more than 9 kilometers across and nearly half the moon’s diameter, making it large enough that the impact that formed it may have come close to shattering the small moon.
The image in the feature is an enhanced-color view recorded by the HiRISE camera aboard Mars Reconnaissance Orbiter during a close pass of Phobos in March 2008, when the spacecraft was about 6,000 kilometers away. NASA says streaks inside the crater suggest loose material has slid down the walls over time.
NASA also says light bluish areas near the rim may mark relatively freshly exposed surface. The origin of the grooves across Phobos remains uncertain; NASA says they may be related either to tidal stresses on the close-orbiting moon or to the impact that formed Stickney itself.
