As MESSENGER approached Mercury on January 14, 2008, the Narrow Angle
Camera (NAC) of the Mercury Dual Imaging System (MDIS) snapped images of
the nearing planet in a sequence that covered the entire sunlit portion of
the surface. This mosaic was made from these images, shown as thumbnails
on the image context sheet released last week (PIA10604).
This mosaic is shown in a cylindrical equidistant (also known as
equirectangular) projection, which simply is a map with longitude lines
being vertical and equally spaced and latitude lines being horizontal and
equally spaced. The mosaic covers the entire approach crescent view of
Mercury (PIA10179), so the vertical extent of the mosaic is
comparable to Mercury's diameter of 4880 kilometers (about 3030 miles).
Surface features on the right side of the mosaic show long shadows that
accentuate height differences because these images were taken near
Mercury's terminator, the transition between the sunlit dayside of the
planet and the dark night side; the previously released image of the
crater Matisse (PIA10190) is an example of one of these near-terminator
images used in the mosaic. Features near the left side of the mosaic are
looking toward the limb of the planet, and this very low viewing geometry
and higher Sun angle do not provide much detail about the surface
structures; the previously released image looking at Mercury's horizon
(PIA10176) is an example of such a view that was used to create this mosaic.
This low-resolution version of the mosaic is only 8% of the resolution of
the full mosaic and contains only one pixel for approximately every 156
pixels in the original images.
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.