MESSENGER's high-resolution images have revealed large areas of Mercury's surface that appear to have been flooded by lava, forming wide expanses of smooth plains. The NAC image shown here gives a view looking over some of these smooth plains toward the horizon in the upper left corner. A large crater in the lower left has been filled with lava such that only portions of its circular rim are visible. Other examples of flooded craters can be spotted throughout the image, along with wrinkle ridges snaking across the plains. "Volcanism on Mercury" is one of the topics being presented today by MESSENGER Science Team members at the Geological Society of America Annual Meeting in Portland, Oregon. Prior to MESSENGER, there was some debate regarding the extent to which volcanism had affected Mercury's surface, but now it is clear that volcanism was a major process in the planet's geological history.

Date Acquired: September 29, 2009
Image Mission Elapsed Time (MET): 162744106
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 400 meters/pixel (0.25 miles/pixel)
Scale: The bottom of this image is about 410 kilometers (250 miles) wide
Spacecraft Altitude: 15,900 kilometers (9,900 miles)

These images are from MESSENGER, a NASA Discovery mission to conduct the first orbital study of the innermost planet, Mercury. For information regarding the use of images, see the MESSENGER image use policy.