31. South Pole Mosaics (First and Second Month Lunar Mapping)

The spin axis of the Moon is nearly vertical (inclined 1.6°) to the ecliptic plane (the plane of its orbit around the Sun), in marked contrast to the Earth (axis inclination 23.5°). However, even this small inclination means that the hemispheres of the Moon experience “seasons,” as the pole tracks toward and away from the Sun. Clementine started its lunar mapping in the dead of southern “winter” (axis away from the Sun), but by the second month of mapping, the axis had begun to point closer in that direction. These two mosaics show the difference in lighting conditions between the first month of mapping (left, maximum winter) and the second month's coverage (right, toward the “solstice”). Careful examination of the two mosaics reveals some slight shadow changes; note in particular the shadows that cover the floors of the craters Amundsen and Scott (large central peak crater at about 3 o’clock and the crater just above it). However, the large region of permanent shadow near the center of the mosaics discovered by Clementine remains virtually unchanged in the two mosaics.

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