238 Encyclopedia of the Solar System FIGURE^12 A mosaic of 1500
ClementineUV VIS images centered
on the South Pole, showing the heavily
cratered south polar region of the
Moon. The Schr ̈odinger Basin (320 km
in diameter), which is the freshest
peak basin on the Moon, is at four
o’clock. Schr ̈odinger is slightly older
than Orientale. Note the small
volcanic cone in the bottom left-hand
sector. It is possible that some ice
(from cometary impacts?) is trapped in
the permanently shadowed craters at
the South Pole. (LP1Clementinepress
release.)
FIGURE 13 Orientale is a classic example of a multiring basin. The
diameter of the outer mountain ring (Montes Cordillera) is 930 km,
about the size of France. Note the radial structures resulting from the
impact. It is the youngest major impact basin on the Moon. This
structure was formed about 3800 million years ago in a few minutes
following the impact of a planetsimal or asteroid about 50–100 km in
diameter. Basalt has flooded the center of the Orientale Basin. The
small circular patch of mare basalt northeast of Orientale is Grimaldi.
The western edge of Oceanus Procellarum fills the northeastern
horizon. (Courtesy NASA, Orbiter IV-187M.)
