Does anyone know why the moon is moving away from earth like two inches each year?

Question

I read some where that the moon is slowly moving away from earth, what do you think will happen?

Answer 1

The reason is gravitational drag. As the moon goes around the earth, it puts forces on the earth and the earth does the same to the moon. A visualization of these forces is the tides. On the moon, it will actually bulge at the "equator" of the moon. This decreases the angular momentum and the "speed" the moon moves around the earth. As it slows down, it moves farther away.

This same effect is slowing down the rotation of the earth.

The effect is small, I don't think it is 2 inches a year.

Answer 2

Yes......angular momentum lost by the Earth is being transfered to the Moon via friction caused by the tides on the Earth's surface. What is happening is that the tides are robbing the Earth slowly of rotational energy and that is consequently be transfered to the orbital angular momentum of the Moon. Hence, each year, the Moon gains 2 inches in its orbital angular momentum and its orbit widens. The Earth's day is progressively getting longer as a result. About 1.6 billion years ago, the Moon was at it's closest approach to the Earth w.r.t. its orbit. At the time, the Moon just lay outside the Roche Limit of the Earth.....around 40,000 miles. Any closer and the Earth would've pulled the Moon apart. It covered several degrees of the sky and the tides were about 40-100 times stronger than today. Earth's rotational velocity was such then that a day lasted only 12-18 hours (it reached 18 hours around 1 billion years ago). Since then, the Moon has robbed Earth of that angular momentum and moved further outwards.

By the time the Sun reaches its red giant stage, the Earth's day will have lengthened out to 36 hours and the Moon will be some 1 million miles away in its orbit. So long as the Moon and Earth aren't destroyed then, time will pass when the Moon and the Earth will show the same face towards one another. By then each day will be about a month or so in length and the Moon several million miles away.

Answer 3

Here's the answer and the source.

Why is the distance between Earth and Moon increasing?
Just like a spinning ice skater whose rotation slows as he extends his arms, the Earth-Moon distance is lengthening because Earth is spinning slower each day. The Moon's gravitational influence is slowing Earth's rate of rotation down by one and a half thousandths of a second every 100 years. The loss of rotational energy -- angular momentum, for the physicists in the crowd -- is necessarily matched by an increase in the Moon's angular momentum, which results in a larger orbit for the Moon.

Currently, the Moon moves less than two inches a year farther away from Earth -- a tiny amount, but easily measurable with modern laser-ranging devices.

Answer 4

It is moving away, but quite slowly... I'm not sure its as fast as 2 inches/year though. The reason its moving away is the same thing that keeps the same side of the moon always facing the Earth, called tidal forces. The force of Earth's gravity tugs on the moon's surface and deforms it like a tide. But because this is solid rock that's deformed, and not liquid, it's gravitationally more favorable to keep the same face towards the Earth.

Now, about the slowing itself. This is called "Tidal Friction". The bulge of the tides on Earth caused by the moon aren't directly underneith the moon, because the Earth's rotation tries to drag it around. Thus, it stays slightly ahead of the moon. As the moon's gravity tugs on the bulge to bring it back into line, it slows the Earth's rotation down. However, the tidal bulge on Earth is also exerting a gravitational pull on the moon, trying to pull the moon forward in its orbit, providing a small acceleration constantly tangent to the moon's orbit. This acts to expand the moon's orbit over time.

Answer 5

there is a gravity interaction between the earth and moon that affects the orbit of both:

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Since the Earth spins faster than the Moon moves around it, the tidal bulges are dragged along with the Earth's surface faster than the Moon moves, and move "in front of the Moon" .

Because of this, the Earth's gravitational pull on the Moon has a component in the Moon's "forward" direction with respect to its orbit. This component of the gravitational forces between the two bodies acts like a torque on the Earth's rotation, and transfers angular momentum and rotational energy from the Earth's spin to the Moon's orbital movement.

Because the Moon is accelerated in the forward direction, it moves to a higher orbit. As a result, the distance between the Earth and Moon increases, and the Earth's spin slows down. Measurements reveal that the Moon's distance to the Earth increases by 38 mm per year (lunar laser ranging experiments with laser reflectors are used to determine this). Atomic clocks also show that the Earth's day lengthens by about 15 microseconds (µs) every year.
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what will happen? the moon will get 38 mm (1 1/2 inches) farther away each year

it will take hundreds of thousands of years at this rate for the change in distance to have any significant effects

Answer 6

The Earth's gravity does pull on the moon, yet no longer sufficient to deliver it in the direction of the Earth. The Moon has a p.c. that that is vacationing. The Earth's gravity causes the Moon to circle round it, rather than fly off into area. The Moon's p.c. is too a lot for the Earth to thoroughly capture, and the Moon is shifting faraway from the Earth at about an inch in accordance to year. in quite some many 1000's of thousands of years, it is going to finally develop into self sustaining from from the Earth and orbit the solar on it is own.

Answer 7

Hi,

They say universe is expanding. Well that is probably the answers.

Althought the moon is now moving 2 inches away from Earth I think even Earth will then move in some direction... close to the moon I assume but it takes much longer time...

Karl
http://www.furl.net/furled.jsp?topic=helloworld

Answer 8

Scientists have spent the last couple of centuries measuring our solar system's planets, neighboring stars, their relation to one another and their paths and determined that the universe is expanding. This means that the area between bodies is increasing. The orbits of the planets and moons is determined by their own mass, the centrifugal force that pushes them away from larger bodies and the magnetic pull of larger bodies that pulls them inward. It is a delicate balance that seems to be fixed and constant , but is far from it. We are gradually moving away from the sun, which is kind of scary but, compared to the alternative of moving closer, a little easier to swallow. As for the effect of the moon's distance increasing, I would expect that the pull, which creates the tides, would lessen by minute degrees. Another effect may be a slight slowing of the earth's rotation which will make our days, seasons and years a little longer. Don't worry, though. These effects are so gradual, and our lifetimes so short, that we will never notice the difference.

Answer 9

Gravity.

There are two modes of energy transfer in the earth-moon system: gravitational waves and gravitational attraction.

Gravitational waves are VERY weak.

The moon transfers its kinetic energy to the ocean, and land tides. Water tides=big & easy to measure, Land tides: a few centimeters, detectible by timing in satellites.

They speed up (yes up) the orbital velocity of the moon. The moon is in a gravitational potential well, so it should be moving farther away as it gains kinetic energy.

Answer 10

the moon is moving away from the earth because the earth's gravity isn't strong enough to keep it close. also, if the moon was closer,our tides would be stronger and our waves would be hundreds of feet high. thats how it was billions of years ago when life was still only single cellular. with the waves being that high,it was kinda mixing the elements and eventually helped in the evolution of multicellular life. so, be happy its so far away.