Why do we always see the same side of the $\mathrm{Moon}$ facing the $\mathrm{Earth}$?

• A. Because the $\mathrm{Moon}$'s rotational period is equal to its orbital period around the $\mathrm{Earth}$
• B. Because the $\mathrm{Moon}$ does not rotate on its axis
• C. Because the $\mathrm{Moon}$'s orbit is perfectly circular
• D. Because the $\mathrm{Earth}$'s gravity prevents the $\mathrm{Moon}$ from rotating

Answer: (A)

Verified step by step guidance

1. Understand that the Moon is tidally locked to the Earth, meaning it shows the same face to Earth at all times.
2. Recognize that this happens because the Moon's rotational period (the time it takes to spin once on its axis) is exactly equal to its orbital period (the time it takes to orbit once around the Earth).
3. This synchronization means that as the Moon orbits Earth, it rotates in such a way that the same side is always facing Earth.
4. Note that the Moon does indeed rotate on its axis; it is not stationary in rotation, but the rotation rate matches the orbital rate.
5. The cause of this tidal locking is the gravitational interaction between Earth and the Moon, which over time has slowed the Moon's rotation to match its orbit.