This image shows a double-ring impact basin, with another large impact crater on its south-southwestern side. Double-ring basins are formed naturally when a large meteoroid strikes the surface of a rocky planet. Smaller, more recent impacts also formed comparatively fresh craters across the entire surface visible in this image. The floor within the inner or peak ring appears to be smoother than the floor between the peak ring and the outer rim, possibly the result of lava flows that partially flooded the basin some time after impact.

This image and caption were prepared by MESSENGER Educator Fellows Christina Dorr (Hilliard City School District, Hilliard, OH) and Julie Taylor (Adelanto School District, Adelanto, CA). For more information on the MESSENGER Educator Fellows program, click here.

Date Acquired: September 29, 2009
Image Mission Elapsed Time (MET): 162744214
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 400 meters/pixel (0.25 mile/pixel)
Scale: The double-ring basin is approximately 160 kilometers in diameter (100 miles)
Spacecraft Altitude: 15,400 kilometers (9,600 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.