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![]() "Mark McIntyre" wrote in message ... On 3 Apr 2006 05:03:04 -0700, in uk.sci.astronomy , "Weatherlawyer" wrote: But anyway its not coincidence, its a local minimum in the energy configuration of two bodies. As the Moon rotates, its rocks are deformed by the gravity of the earth. This absorbs energy. Eventually, the energy loss caused the rotation to slow. Once the orbital speed and rotational speed 'matched' the rocks stopped being distorted, no more energy was lost, and a stable state was reached. The same is happening to the Earth by the way, and to many other moons in the solar system. Mark McIntyre -- Yes. Charon and Pluto are locked too; (no comments as to whether Pluto is a planet please). More to the point, ALL other known moons in the Solar System are gravitationally locked to the parent planet, except Phoebe. In addition: Mercury is locked to the Sun, actually a 3:2 spin-orbit resonance which accounts for it's large libration. And Venus is locked to the Earth so that at closest approach it always has the same side facing us. Not only is the orbit (year) of Venus in a 5:8 resonance with the Earth year, but its rotation (day) is in a 3:2 resonance with the Earth year. All this talk of coincidence and divine design is pure codswallop, taking no account of natural mechanics. All the orbital distances and periods are related geometrically for the same reason that a pendulum swings in simple harmonic motion. |
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