NASA Mars Picture of the Day: Arsia & Phobos

This pair of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC)
color images shows early autumn clouds over the Arsia Mons
volcano, plus the shadow of the innermost of the two martain
moons, Phobos. The picture on the left is taken from the MOC
daily global map acquired at 7.5 km (~4.7 mi) per pixel on
28 January 2006, about a week after the start of southern
autumn. The picture on the right was taken at the same time,
but at a higher resolution of 489 m (1604 ft) per pixel.

Both pictures are composites of MOC red and blue wide angle
images, and both are oriented such that north is up and east
is to the right. Arsia Mons and the other large Tharsis volcanoes
commonly develop afternoon orographic (i.e.,
topographically-controlled) water ice clouds at this time of year.
The equatorial Tharsis volcano, Pavonis Mons, is also under a deck
of water ice clouds; it is located toward the upper right corner of
the left, lower-resolution image.

Sunlight glints off the dusty surface and the clouds and
aerosols in the atmosphere,
producing the bright diagonal streak located just southeast
(lower right) of Arsia Mons. A water ice haze is seen on the
left side of the lower-resolution image. The dark oval to
the northeast of Arsia Mons, as noted above, is the shadow
of Phobos.

Additional View:

• Same picture, without annotation