Astronomical OverviewMoon
Fig. 4.4 Moon FieldThe moon is, in fact, not a planet but a satellite of the earth.
Since the moon has no protective atmosphere it has been bombarded out in space for
the last 800 million years. The craters that we can see from the earth are ‘scars’ of this
activity, their presence enabled by the absence of erosion. Stones have been found that
are more than 4 billion years old, the same age as the solar system. The origin of the
moon in relation to the earth is still a mystery. Its rotational speeds around its axis and
around the earth are about equal; 28 days. For this reason we always see the same side
of the moon. Temperature extremes vary between + 127 °C and - 173 °C.