Where is the energy of the tides lost from, does the sun and moon lose energy somehow?

Question

I know that the gravity of the sun and moon cause the tides, the energy that is required to cause the tides must be taken from some where else, where is it? Is it lost from the sun and moon some how? I'm thinking maybe the moons revolution around the earth is slowing or something like that. What about the sun? Thanks for any answers.

Answer 1

Forget the sun...its gravity pull is neglible. Its the moon that really pulls the tides.

The moon's gravity essentiall pulls the liquid from a body of water up to a point perpendicular to itself. In other words, if the moon is directly above a large circular lake, it pulls the water up, creating a "bump" in the middle of the lake, and a receding tide at the edges of the lake.

The "bump" represents stored potential energy.

When the moon moves on, the pull weakens, and the bump returns back to the rest of the water, essentially making the pool/lake flat again. The stored potential energy is slowly returned back to zero.

Answer 2

No, the Sun is not responsible for the tides like the Moon is.

It's all about mass AND proximity.

Your statement that "the energy that is required to cause the tides must be taken from some where else, where is it?" is misdirected.

A lot has been written about the Moon's effect on the tides. Recently, an epiphany occurred regarding the effect of the Moon and the tides on the Earth's rotation. Scientists have determined that the Moon pulling on the ocean tides is having a braking effect on the rotation of the Earth -- about 2 to 7 one-millionths of a second every year. No big whoop, but archeologist have found evidence of ancient cycles supporting the idea that about 370 million years ago, the Earth rotated faster; that a solar day lasted 20 hours and about thirty-five minutes. Actual measurements of Earth's rotation have now been taken to back up the "braking" claim.

But, now, let's look at the "other side of the coin".

Measurements of the Moon's behavior have revealed that the Moon is literally "inching" its way out away from the Earth -- about one and a half inches per year. I've not read the explanation, but I can tell you from my professional perspective that the "braking" effect the Moon is imparting on the Earth's rotation is being transferred to the Moon's orbital energy. In other words, the Earth, in turn, by the tidal effect, is causing the Moon to very slowly gain angular momentum. This translates into a ever so gradual higher orbit.

In some ways, I see this as analogous to a gigantic automatic transmission torque converter in which fluid mass (in this case, ocean water) is being used to transfer energy from the engine (Earth) to the transmission (the Moon) -- the linkage being the gravitation field between Earth and the Moon.

I hope this helps clear the mud.

Answer 3

You could break it down to some nitty-gritty examinations to see exactly HOW it's being transferred, but your question is in a pretty good ball park. Good to see people out there thinking about things in stead of just sitting on the edge of their seats to see Paris Hilton's release from jail.

Actually, I don't think the rising of the tide represents a change in energy. When between the Earth and The moon, the Moon's gravity field is canceling out a bit of the Earth's, so being higher in the Earth's gravity field would be the same amount of potential energy as a lower altitude at a location not weakened by the lunar gravity. The rising tide is basically a maintaining of the status quo.

What is happening though, is that there is a bit of lag between where the tide actually is, and the spot the moon is directly above. This difference creates a torque on the Earth, since a part of it is closer, and being attracted directly towards the moon. This creates a force line not directly through the center of the earth - ergo, torque. (force X lever-arm)

This torque slows down the Earth's rotation. And as you've realized - energy has to come from somewhere, and it has to go somewhere else. It doesn't just appear and it doesn't just vanish. When the Earth loses rotational velocity / energy, it does go somewhere - into the object causing the torque: the Moon. This energy, once transferred, manifests itself by the Moon speeding up a bit (a lot like probes getting gravity assists from flying by other planets, only this small bump in the earth doesn't give a whole lot of boost to the moon, mind you, but it does add up over eons.). This speed, in turn causes the moon to get further from the Earth.

Eventually, the moon and the Earth will be locked - the moon will be geostationary - always over the same spot. The Earth will be rotating a lot slower, and the moon will be orbiting a lot further from the Earth, with a longer period of orbit than we have today.

Imagine the figure skater spinning on the tips of her skates. As she pulls her arms in, she spins faster. As she moves them away from her body, she slows down again. This is exactly the same phenominon that the Earth-Moon system is undergoing.

All in all, no energy is being gained or lost from the whole system, though. It's just moving across the back yard over to the moon.

Answer 4

its just a low ammount of energy lost since earth and moon both rotate around a center of mass.
This energy is only some friction caused by the movement of both water and surface up and down.

In fact theres some energy lost in this which results in the moon slowly drifting away from earth about an inch per year and a loss in rotation speed for both earth and moon.

One theory states that this loss has caused the moon to catch up with earths rotation over the millions of years this is already happening, resulting in having the moon always showing us the same side.

The Drift-off has been found with laser-reflectors on the surface brought in place with some Apollo-Missions in the 70's

effectly the loss is just small because one can imagine the whole scenario as a kind of low-frequency vibration in the moon-earth system, so its just some friction.

Answer 5

Because Earth is rotating faster than the Moon orbits Earth, there is a coupling between the orbit of the Moon and the rotation of the Earth in such a way that energy of the Earth's rotation is being transferred to energy of the Moon's orbit, causing the Moon to orbit out a couple inches farther every year and the day on Earth to get a tiny fraction of a second longer each year.

Answer 6

Trying not to make a long winded explanation but something simple. The energy is stored in the mass of the moon as it revolves around the earth. It is balanced, any more and the moon would crash into the earth and any less it would drift away.

Answer 7

The energy goes for the spinning rate of the bodies in question. The earth used to have much shorter days--it was spinning much faster billion of years ago. And days will have more hours in them billions of years from now, as the earth spin continues to slow down.
This energy is transferred to the moon, which drifts further.
And the same is true for the sun: slower spin, slowly drifting away planets.

Answer 8

The energy from the tides is gravitational energy derived from matter. When matter was created at the beginning of the universe, there was some loss of energy which was transfered to the gravitational energy you experience. This energy debt will and must be paid back and this occurs when matter is converted to energy (like in the stars, Hawkings radiation, and nuclear reactions)

Answer 9

It actually is involved in slowing the Earth's rotation.