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Message: <blockquote data-quote="J_D" data-source="post: 1924628" data-attributes="member: 20956">Actually, the ellipticity of the orbit in and of itself has nothing to do with tides.  It's all about gravity and rotation.  Remember that the strength of the gravitational force is inversely proportional to the square of the distance.  The closer you are, the stronger the pull, and the farther away the less strong the pull is.  Now, remember that planets and moons are not point objects - they take up space.  Tides come from the fact that the gravitational pull a body exerts on the nearest side of another body at a distance is a bit stronger than the pull that same first body exerts on the farthest side of the other body.  That difference in gravitational pull is what a tide is.On a solid body, this tidal force acts over time to slow down the rotation of the distant body.  Angular momentum is a quantity that is conserved, though, so the lost angular momentum must go somewhere and it does - into the orbit between the two bodies.  As the rotation of the bodies slow, the size of their orbit increases.  Eventually both bodies will either be tidelocked to each other (i.e. show each other the same face constantly), or the orbiting body will leave the orbit and go off on its own.  Without the moon, the Earth would spin a lot faster and our day would be a lot shorter.  Over time, our day is slowing and this is driving the moon away from us.  The moon is tidelocked to the Earth already because the Earth's gravity is much stronger, but eventually the Earth will be tidelocked to the moon as well.  That, or the moon will get far enough from the earth to leave orbit.  I'm not sure which would happen first.When a world has a fluid on the surface, though - liquid oceans, for example - the tidal force causes the fluid to bulge both toward and away from the body exerting the tidal force.  There will be "bulges" on the near side and far side relative to the more rigid solid surface, and shallow points in the middle.  These bulges stay aligned with the tide-generating body, and the planet rotates underneath them.  Thus, there are two high tides and two low tides each day.The only possible effect the moon's eccentricity would be is to affect the severity or degree of the tidal difference over time.  When the moon is closer, it'll exert a greater tidal force thus the high tides will be a bit higher and the low tides will be a bit lower.  When the moon is farther away, the difference between high and low tide will be lessened.  The moon's eccentricity will affect the degree of the tides, but has nothing to do with the cause of the tides.  I'm not going to go into the math here, but the way the math works out the degree of the "tidal force" is inversely proportional to the cube of the distance, which is different than just the basic gravitational attraction between two masses.  To get a tidal force twice as strong the moon would need to be eight times closer.  What I can't say for sure is whether the "tidal force" is directly proportional to the height in feet of the ocean tides.</blockquote>

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