Orbit of the Moon the Moon varies as it orbits Earth and hence is not always equal to the Moon's rotational velocity. When the Moon is at its perigee, its rotation is slower than its orbital motion, and this allows us to see up to eight degrees of longitude of its eastern (right) far side. Conversely, when the Moon reaches its apogee, its rotation is faster than its orbital motion and this reveals eight degrees of longitude of its western (left) far side. This is referred to as "longitudinal libration". Because the lunar orbit is also inclined to Earth's ecliptic plane by 5.1°, the
Around the Moon to Earth. During the latter part of the voyage, it becomes apparent that the gravitational force of their earlier encounter with the asteroid has caused the projectile to deviate from its course. The projectile enters lunar orbit, rather than landing on the moon as originally planned. Barbicane, Ardan and Nicholl begin geographical observations with opera glasses. The projectile then dips over the northern hemisphere of the moon, into the darkness of its shadow. It is plunged into extreme cold, before emerging into the light and heat again. They then begin to approach the moon's southern hemisphere. From the safety of