One solar day on a planet is the length of time
from noon to noon.
A solar day lasts 24 hours on planet Earth.
On Mercury a solar day is about 176 Earth days long.
And during its
first Mercury solar day
the MESSENGER spacecraft has
imaged nearly the entire surface of the
to generate a global monochrome map at 250 meters per
pixel resolution and a 1 kilometer per pixel resolution color map.
Examples of the maps, mosaics constructed from thousands of
images made under uniform lighting conditions,
are shown (monochrome at left), both centered along the
planet's 75 degrees East longitude
The MESSENGER spacecraft's second Mercury solar day will
likely include more high resolution
of the planet's surface features.
(Editor's note: Due to Mercury's 3:2 spin-orbit
resonance, a Mercury solar day is 2
Mercury years long.)