A Spider Shaped Crater on Mercury . ... Credit Copyright: MESSENGER , NASA , JHU APL , CIW Explanation: Why does this crater on Mercury look like a spider? When the robotic MESSENGER spacecraft glided by the planet Mercury last month, it was able to image portions of the Sun's closest planet that had never been seen before. When imaging the center of Mercury's extremely large Caloris Basin , MESSENGER found a crater, pictured above , with a set of unusual rays emanating out from its center. ...