does the earths moon spin on its axis and if so why do we never see the darkside of the moon or its other side

Question

We all know the familiar side of our sattilite but Ive heard that the moon does spin on its axis, please explain!

Answer 1

The moon's rate of revoulution is such that it spins one time over it's orbital period. That means that you are correct, that the same face of the moon always faces the Earth. But it does spin.

Answer 2

The Moon, of course, rotates--at the same speed as it orbits the Earth. So, in the 27.32 days it takes the Moon to go around Earth, the Moon also spins about its axis one full revolution. That's why we always see the same face of the Moon.

Now, the interesting part: why does the Moon spin about its axis at the same rate it orbits? In the distant past, the Earth's tidal pull on the Moon slowed the Moon's rotation to match the time it takes to go around Earth.

This is tricky stuff. You know about the tides on Earth. The same forces work on the Moon. It isn't obvious there because the Moon lacks water but it happens. The Earth's gravitational attraction is stronger on the side of the Moon nearest to Earth and weaker on the opposite side. Since the Moon isn't perfectly rigid, it stretches out, like a ball of taffy, along the line between Earth and Moon. If we were on the Moon, we could, theoretically, see two bulges--one on the side facing Earth and the other directly opposite.

Long ago when the Moon spun much faster, the Moon's tidal bulge preceded the Earth-Moon line because the Moon couldn't "snap back" its bulges quickly enough to keep its bulges in line with Earth. The rotation swept the bulge beyond the Earth-Moon line. This out-of-line bulge caused a torque, slowing the Moon spin, like a wrench tightening a nut. When the Moon's spin slowed enough to match its orbital rate, then the bulge always faced Earth, the bulge was in line with Earth, and the torque disappeared. That's why the Moon rotates at the same rate as it orbits and we always see the same side of the Moon.

In our solar system, almost all moons spin at the same rate as they orbit. We think the exceptions are ex-asteroids captured so recently that tidal forces have not yet equalized the orbital and rotational periods.

Answer 3

Thanks for such a thought provoking question!
Parts of this answer are easy: The Moon does spin on its axis. We do see the dark side during the phases of the moon: The New Moon, Crescent Moon, Full Moon, and Waning Moon.

The last part is not so easy: "Or its other side" Why don't we see the other side of the moon. One answerer said it is because tidal friction has slowed the moon until one side always faces Earth. Good guess, and probably partially correct in that it it relates to the polarity of the gravity field and how opposite sides of the Earth and Moon might be bulging or elongated. The deeper answer has to do with the inner structure of the moon and how its imbalance results in a Moon that always has one side that faces 'down.'

I believe in the theory that the Moon is a result of an ancient collision between the Earth and another celestial body. Debris from that collision became the Moon. When two bodies collide, the forces generated can destroy either one, or both of the objects. In this case, one object was destroyed and part of its remains became part of Earth and part of it became the Moon. Probably some of Earth was blasted out into space and may have become part of the Moon as well. At any rate, the two bodies which had formed out of the dust of the early Sun's dusty accretion disk as nearly perfect spheres came together and mixed their different parts together in a fiery blast which left both of them imperfect.

The Earth's response was an internal imbalance of energy that has been powering the creation of continents and continental drift over the last several billion years.

The Moon formed out of the remains that were ejected into an orbital path around the Earth. The largest chunk gathered up the rest and grew in size until it became the moon we have now, several billion years ago. The last small chunks left impact craters all over the Moon's surface. The Earth is about 80 times larger than the Moon. Most of it is Iron, and molten iron at that. It is much more homogeneous than the Moon, which is a jumble of chunks, including iron probably that was blasted off the Earth. Mass is not evenly distributed throughout the Moon's structure.

An analogy: When a body is submerged in water, it takes the place of the water in the space used by the body. Water has weight. The body has weight. If the weight of the water is more than the weight of the body, the body will rise up and float on the surface of the water. If the weight of the body is more than the weight of the water, it will sink to the bottom of the water. But if the weight of the body is the same as the weight of the water, it will just float in place. But here's the point: Even though the body floats in place, neither sinking nor floating, the heaviest part of the body will turn the body so that the heavy part is toward the bottom and the lighter part is toward the top. This is a result of gravity's polarity, the 'up-ness' and 'down-ness' that is part of the way gravity works. Heavier goes down, and lighter goes up. This can also be seen in a hot air balloon. the heavy wicker basket with the passengers stays at the bottom and the hot (lighter) gas inside the balloon tends to go to the top.

The moon, in orbit around the Sun and the Earth is in a state similar to neutral buoyancy of a body in water in its orbit around the Earth. The Earth's gravity is stronger - at the distance of the moon, than the Sun's. And the Moon's mass is not sufficient to keep it spinning in the Earth/Moon gravity's polarity. So the Heavy side of the Moon faces 'down' and the lighter side faces 'up.' Since it is caught in a gravitational bond with the Earth, 'up' and 'down' to the moon are on a line drawn between the Moon's and Earth's centers of mass. If you were standing on the Moon, the Moon's gravity would be much stronger than the Earth's at that distance, and up and down - to you - would be on a line pointing toward the Moon's center of mass.

The Earth's mass is sufficient to keep it spinning against the polarity between the Earth and Moon. The only result on Earth is a minute slowing of the Earth's rotation, and the ocean's tides.

;-D The Moon is the Heart of Romance! Enjoy it!

Answer 4

All things in the orbit of the solar system spin in their own orbit as they spin around the sun. They all spin on their axis, except Uranius which spins on it's side. We eventually see both sides of the moon as it's always spinning, but the darkside of the moon is only the part that's being blocked out by the sun as it faces away from us that particular night. It's never the exact same side that shows to us every night. It's all part of Newton's laws.

Answer 5

Yes, it does, and it takes a month for one revolution. Think of it going from full moon to full moon, always keeping the same hemisphere facing earth. To do that, it must revolve once ... actually a bit more than once, since the earth-moon-sun relationship changes by about 30 degrees (30 deg. x 12 months = 1 year) during that time, and also because it's about 29 1/2 days (less than a month) between full moons.

Answer 6

The moon does spin on its' axis, one spin every 28 days, so we always see only the one side of it. That's because it takes the moon 28 days to rotate completely around the Earth. I believe the phrase is "tidal locked" but don't quote me on that.

Answer 7

Yes it spins on its axis, but it also orbits the earth. It does both in unison (once every 28 days) so that the same side is always pointing to the earth.

Answer 8

The moon doesn't spin. It's geosynchronous. Always facing the same way.

Answer 9

We do see the dark side. It's that it turns at the same rate that it orbits the sun. That's why there's a dark side to it.