Kerwan Crater

Kerwan Crater
Kerwan Crater Ceres’ largest crater is Kerwan, which fills most of this picture. The crater is 174 miles (280 kilometers) in diameter. That may seem large, and indeed it is large compared to all other Cerean craters and probably also compared to the block you live on and the landscape you can see out your window (unless you happen to have a view of the moon). But as we have discussed before, scientists recognize that Ceres should have even larger craters. Those ancient craters probably were erased by the gradual movement of the ice and rock in the ground as it "relaxes" after a disfiguring impact, just as your skin restores its shape after pressure has been removed. That process is stronger for larger craters and likely contributed to making Kerwan’s features appear softened. Kerwan is noticeably polygonal because the crater walls formed along preexisting underground fractures when the impactor struck, and we will see another example of that below. Dawn took this picture on June 12, 2015, from an altitude of 2,700 miles (4,400 kilometers) in its second mapping orbit. We have seen Kerwan from a different perspective as well as a close-up of one area in it photographed from Dawn’s lowest altitude orbit. (The crater is so large that it took about 50 pictures from low altitude to cover it.) Below is a photo of the center of Kerwan from an intermediate altitude. The crater at the center is Insitor, which is 16 miles (26 kilometers) in diameter. (Insitor was a minor Roman god concerned with sowing crops. Perhaps his being minor is appropriate, as the crater is less than 1 percent of Kerwan’s area.) You can locate Kerwan at 11°S, 124°E on this map. The dark material at the upper right of this picture was blasted out by the impact that formed Dantu Crater, which we will see belowFull image and caption. NASA / JPL-Caltech / UCLA / MPS / DLR / IDA

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