I understand tidal lock, but if the Moon does actually rotate on it's own axis, doesn't rotation mean it spins a full 360-degrees, thus showing it's entire surface to Earth as it rotates?
2007-07-28 08:16:15 · 16 answers · asked by uspsorbust 1 in Science & Mathematics ➔ Astronomy & Space
I lay on my patio alot at night staring at the moon when it's out wondering the same thing!
well then i'm awake all night all mindblown lol
2007-07-28 08:23:03 · answer #1 · answered by Anonymous · 0⤊ 3⤋
The answer lies within your question. Tidal lock. More specifically Tidal Coupling and Gravitational Locking.
The reciprocal induction of tides in the Earth and Moon leads to a complicated coupling or the rotational and orbital motions of the two bodies. Tidal coupling tends to synchronize them. This is called gravitational locking. As the objects revolve around the barycenter, the effect is also slowing Earth's rotation and causing the Moon to move farther away as a way to conserve angular momentum.
This is a process occuring over billions of years so one may presume that there was a time billions of years ago when the Moon did show it's entire surface as seen from Earth.
The end result being that the Earth and Moon will have the exact same rotational period which will equal the orbital period. In simple terms, the Earth will keep the same face turned toward the Moon just as the Moon presently keeps the same face towards Earth.
By then, not many people will be able to see it because the Sun will be entering it's Red Giant stage.
2007-07-28 16:30:01 · answer #2 · answered by Troasa 7 · 0⤊ 0⤋
Think of it this way:
The Moon moves in a (rough) circle around the Earth as it rotates. When it has rotated ten degrees around its own axis it has also moved ten degrees around its orbit. By the time it has rotated ninety degrees it has also moved ninety degrees around the Earth. As it turns, so it moves, and the result is that the same face always points to Earth. You would see all the Moon if it moved in a circular path without rotating, because by the time it got 180 degrees around the Earth it would be facing the other way.
And contrary to an earlier enaswer, our Moon is certainly not the only moon to do it. In fact nearly all moons in the solar system are tidally locked. Pluto and Charon are in fact tidally locked to each other, so that no only does Charon always show the same face to Pluto, Pluto always shows the same face to Charon.
2007-07-28 17:13:38 · answer #3 · answered by Jason T 7 · 1⤊ 0⤋
It is because the Moon rotates exactly one revolution per Lunar month that we do see the same side of the Moon at all times. If it did not rotate, we could see all areas of the Moon's surface over time. The Moon is in geosynchronous orbit around the Earth.
2007-07-28 19:37:39 · answer #4 · answered by NJGuy 5 · 1⤊ 0⤋
The motion of the moon is very interesting. Relative to the earth its orbit is eliptical inclined 5 degree from the Ecliptic.
It is perturbed by the Earth.
From a frame of reference on the earth we see the moon at night reflecting the Sun's ray just like a mirror.
So to be a good mirror it needs to face us all the time. And it actually does we do see the same face continuously.The reason why this happen is as follows;
The Moon also orbits the Sun as well as the Earth .
The Moon's orbit around the Sun as viewed from a star is in the form of 13 cycloidal periods of motion. Each period is called a month. Each month in the period consists of aprox. 27.3 sidereal days. The spin period of the moon on itself is 27.5 days . For this reason since its spins at the same speed of the monthly cycle orbiting around the Sun, the moon appears to face us always from the same side.
The New moon is not visible at night because its on the other side of the Earth and is only visible during the day.
2007-07-28 15:48:28 · answer #5 · answered by goring 6 · 1⤊ 0⤋
The moon rotates on its axis, which the rotates around the earth (just as the earth rotates around the sun). But it rotates at such as speed that the same side is always showing. You can think that it rotates and circles the earth both once... during every revolution.
2007-07-28 16:10:55 · answer #6 · answered by nate q 3 · 2⤊ 0⤋
The Earth and the Moon are tidally locked so that the Moon's orbital period is the same as it's rotational period. This dictates that the same side will always face the Earth.
2007-07-28 19:04:12 · answer #7 · answered by clitt1234 3 · 0⤊ 1⤋
since the moon takes approximately 28 days to circle the earth and the same side is facing the earth it must rotate once on its axis in exactly the same amount of time. think of the tip of one of your fingers as the earth and hold your cell phone (the moon) in the other hand, keep the front of your cell phone facing the earth and you will see that in one circle around the earth the moon will rotate once with respect to its starting point.
2007-07-28 15:45:27 · answer #8 · answered by ytarmrellim 1 · 1⤊ 0⤋
The same side of the moon is always seen by us on Earth because as it is true that it rotates (spins) on it's axis (it spins on its axis one "spin" in a month) it is, at the same time, revolving through its orbit around the Earth (also once in the period of a month).
2007-07-28 15:24:36 · answer #9 · answered by RubberDuckie 1 · 3⤊ 0⤋
Try an experiment: Walk around a tree, rotating your body so that itmakes a complete rotation as you walk around the tree once. You should notice that your front is always facing the tree.
2007-07-28 15:35:47 · answer #10 · answered by Renaissance Man 5 · 1⤊ 0⤋
You're wrong, it does not rotate on it's own axis, it only rotates around the Earth (because it is on synchronous rotation) and completes one orbit in 30 days more or less.
2007-07-28 15:24:08 · answer #11 · answered by Anonymous · 0⤊ 4⤋