If a satellite loses energy it starts to circle lower and finally hits the atmosphere. The moon is moving like an inch a year away from the earth even though it is losing energy pulling the oceans around.
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- The total energy remains always the same, due to the energy conservation. 2) The satellite loses potential energy and gains kinetical energy, the second is lost due to atmospheric drag. This is why the satellite decelerates. Without an atmosphere, it would accelerate.
– peterh May 27 '19 at 10:43 -
If your pants are loose you'll lose them. – David Hammen May 27 '19 at 12:35
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Satellites that orbit close enough to a planet to interact with the planet's atmosphere lose energy due to that interaction. The Earth's Moon orbits so far away from the Earth that there is essentially no atmosphere with which the Moon can interact. – David Hammen May 27 '19 at 12:53
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1The Earth's Moon does interact with the Earth in other ways. The most significant is of course gravitation, which keeps the Moon in orbit. A more subtle way is tidal interactions. The Moon is slowly slowing down the Earth's rotation rate. It is the Earth that is losing energy, not the Moon. This loss of rotational energy has to go somewhere, and that somewhere is primarily to the Moon. – David Hammen May 27 '19 at 12:53
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This happens throughout the solar system. Satellites that orbit faster than the parent planet rotates spiral inward toward the planet due to tidal interactions. Satellites such as the Earth's Moon that orbit further out spiral outward. – David Hammen May 27 '19 at 12:53
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No. The energy budget of the Moon is actually increasing. The Earth's spin is slowing down, and that energy gets transferred to the Moon.
Why is the Moon receding from the Earth due to tides? Is this typical for other moons?
Whatever else may be happening (like the losses you mention), this transfer from Earth's spin to Moon's orbital energy is the main process responsible for raising the Moon's orbit.
Florin Andrei
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1Think of the rapidly spinning Earth carrying the tidal bulges ahead of the slowly orbitting Moon. The gravitational pull of the bulges pulls the Moon forwards in its orbit, adding energy. – Steve Linton May 27 '19 at 10:34
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@SteveLinton - Those tidal bulges of which you wrote do not and cannot exist. The tidal bulges are instead a lie told to children. Getting the science right is ridiculously complex, and hence the lie to children (and even to scientists). This answer is simple enough and is correct. The Moon is not losing energy. The Earth however is losing energy, and that energy has to go somewhere. That "somewhere" mostly is to the Moon. – David Hammen May 27 '19 at 12:13
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If this is not the mechanism by which that energy is transferred to the moon, what is? – Steve Linton May 27 '19 at 12:33
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@SteveLinton - Tidal interactions are the mechanism. The nonexistent tidal bulges are not. – David Hammen May 27 '19 at 12:47
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@DavidHammen, so how are tidal interactions the mechanism? Something must provide a net gravitational force on the Moon forward in its orbit. – Steve Linton May 27 '19 at 13:09
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@SteveLinton - The easy and correct answer is conservation of angular momentum. The Earth's rotation rate is slowly decreasing. The vast majority of this decrease is the result of tidal interactions in the north Atlantic. This angular momentum has to go somewhere as angular momentum is a conserved quantity. Does the exact mechanism matter? The exact mechanism is hairily complex. Invoking the conservation laws is beautifully simple. Using a lie -- that's just ugly. – David Hammen May 27 '19 at 13:19
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