Multiple choice

Only one side of the moon is seen from the earth because

  1. the moon is at perigee

  2. the moon does not rotate

  3. only one side reflects light

  4. the periods of rotation and revolution of the moon are equal
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The Moon is tidally locked to Earth, meaning its rotational period (27.3 days) exactly equals its orbital period. This synchronous rotation causes the same lunar hemisphere to always face Earth. The far side was not seen until spacecraft missions in the 20th century. The Moon does rotate, just at the same rate it orbits.

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