The Rays that appear in this highly suggestive Limb image of Mercury come from Debussy, the sharp Crater well visible near the Terminator (such as the "line" separating the Dayside of a any given Celestial Body from its Nightside). This dominant Crater was also a part of NASA - MESSENGER's first historic image of Mercury : such the first frame ever taken from a Spacecraft in orbit about this Planet. Readers may also notice the presence of a very faint streak in the blackness of Space, visible near upper left corner of the frame. This artifact was produced by a Cosmic Ray which hit the camera's CCD detector while the image was still being collected.
This frame was acquired as part of MDIS's Limb imaging campaign: once per week, MDIS captures images of Mercury's Limb, with an emphasis on imaging the Southern Hemisphere's Limb. These Limb images provide information about Mercury's actual shape and complement measurements of topography made by the Mercury Laser Altimeter (MLA) of Mercury's Northern Hemisphere.

Date of acquisition: July, 26th, 2011
Image Mission Elapsed Time (MET): 220137668
Image ID: 550504
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC filter: 7 (748 nanometers)
Center Latitude: 27,90° South
Center Longitude: 29,17° East
Resolution: 2783 meters/pixel
Scale: Mercury's radius is approximately 2440 km (about 1515,24 miles)
Solar Incidence Angle: 65,1°
Emission Angle: 48,2°
Sun-Mercury-Spacecraft (i.e.: "Phase") Angle: 95,3°