A small impact crater on Mars named Gratteri, 4.3 miles (6.9 km) wide, lies at the center of large dark streaks. Unlike an ordinary daytime photo, this nighttime image shows how warm various surface areas are. Brighter tones mean warmer temperatures, which indicate areas with rockier surface materials. Darker areas indicate cooler and dustier terrain. For example, the bright narrow rings scattered across the image show where rocks are exposed on the uplifted rims of impact craters. Broad bright areas show expanses of bare rock and durable crust. Fine-grain materials, such as dust and sand, show up as dark areas, most notably in the streaky rays made of fine material flung away in the aftermath of the meteorite's impact.
Image Credit: NASA/JPL-Caltech/Arizona State University
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