Gratteri Crater, 4.3 miles (6.9 km) across, has a ray pattern whose most distant rays reach about 450 miles (600 km) and perhaps farther. Lunar rays appear bright, but Gratteri’s look dark because the image was taken at night by thermal infrared light. In the infrared, rocky areas are bright because they still hold daytime warmth. In contrast, dark streaks and patches show where fine-grain material has cooled after local sunset. Unlike other ray craters, Gratteri occurred in ancient terrain and may be the source of the oldest Mars meteorite, ALH84001.
NASA / JPL / ASU / University of Tennessee