Caloris Basin on Mercury seen by the Messenger spacecraft

Credit: NASA/JHU/APL/ASU/CIW

Messenger flew by Mercury on January 14, 2008, before it returned to orbit Mercury and extensively map the surface. In this image the 1550 km diameter crater shows in yellow hues. The orange splotches on the perimeter are thought to be volcanic vents. This crater was discovered by the Mariner 10 spacecraft a decade earlier.