The moon revolves around the earth, but doesn't rotate/spin on its own axis. Why not?

After all, the earth revolves around the sun AND spins on its own axis.

9 Answers

  • 1 decade ago
    Best Answer

    The moon DOES rotate. The reason you cannot detect it is because it is in a synchronous rotation, meaning that it takes the same ammount of time to revolve as it does to rotate, meaning that the same face (the Light side) is always facing us. It may be hard to visualize at first, but imagine you are the moon. Now, stand facing an object, like a pole which will be the Earth. Now, practice spinning around (revolving) so that you can do it in exactly 10 seconds. Now, practice walking around the pole so that you are rotating for exactly 10 seconds. Now, do them both together. From your perspective (as the moon) you ARE rotating, but you'll notice that your face (the Light side of the moon) is always facing the Earth.

    Source(s): Common knowledge
  • 4 years ago

    When you are in a car, train, or airplane, you can move around comfortably even though the vehicle is hurtling along. It's the same way with the Earth. The surface velocity relative to the center is a bit more than 1,000 mph at the equator, which counters gravity there *slightly*, making Earth an oblate spheroid (flattened at the poles). But everything on the Earth including oceans and atmosphere is spinning along with it. The only noticeable effect is when something moves north or south, there is a small force that curves its path (often called the Coriolis effect). This leads to wind and ocean current patterns, including hurricane direction. Similarly, Earth moves in its orbit at almost 30 km/s (over 100,000 mph!), but since everything is moving with it, we don't notice. Earth's rotational and orbital velocity *does* have to be taken into account when we launch spacecraft, since we need to calculate thrusts and directions relative to whatever the destination is. And you could go beyond the Solar System to note that the Sun is in orbit around the galaxy and the galaxy is speeding toward the Andromeda galaxy, but we are all going along for the ride.

  • 1 decade ago

    Yes the moon does rotate in such a way that its year and day are exactly the same. For the moon to orbit the Earth and keep the same side facing the Earth it would have to rotate in just the right way. Gravitational tidal forces over time make it that way. Called a geosynchronous orbit.

    Think about this. If you face your computer monitor and then walk over to its right side without rotating you would be facing the space behind the monitor. In order to face the monitor you would have to rotate.

  • 1 decade ago

    The moon DOES in fact rotate on its own axis. It just does it with a speed such that only one side ever shows to earth. This is called synchronous rotation. It takes the moon exactly as many days to rotate on its axis as it does to revolve around the earth.

    This happens to many moons of many planets, not just ours!

    (By the way, if it did NOT rotate on its own axis, we'd see more than one side of the moon due to our own rotation and elliptical orbit.)

    Source(s): prior knowledge verified by wikipedia KEYWORDS: Synchronous rotation
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  • 1 decade ago

    It does spin with the same speed as the earth. More moons than ours do this in the solar system. It's due to the mutual transfer of energy between rotating bodies (Tidal effects). This link explains in more detail.

  • 1 decade ago

    Due to the larger gravitaional pull by the earth mooon rotates around it. But it has not discoverd why the moon didin't spins on its axis.

  • 1 decade ago

    Earth is spin stabilized, so it has to spin in its axis to maintain stability.

    But moon is gravity gradient stabilized, so it is not revolving in its axis.

    Source(s): My Understanding
  • Anonymous
    1 decade ago

    It's gravitationally locked in sync with Earth.

  • 1 decade ago

    coz thats how satellites work look up satellites and projectiles

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