DutchE Posted December 10, 2003 Share Posted December 10, 2003 i asked when you think the moon stopped spinning. well i think it was 65 million years ago. Link to comment Share on other sites More sharing options...
blike Posted December 10, 2003 Share Posted December 10, 2003 but the moon is spinning. just not relative to us. Link to comment Share on other sites More sharing options...
wolfson Posted December 10, 2003 Share Posted December 10, 2003 Yep Blike has it there. Link to comment Share on other sites More sharing options...
DutchE Posted December 10, 2003 Author Share Posted December 10, 2003 i mean, as it is today, tidally locked. but when did it lock? Link to comment Share on other sites More sharing options...
Sayonara Posted December 10, 2003 Share Posted December 10, 2003 Isn't it the tides that are lunarly locked? It made me laugh. Link to comment Share on other sites More sharing options...
gene Posted December 10, 2003 Share Posted December 10, 2003 The moon is spinning all the time, isn't it? We still have tides. Don't we? Link to comment Share on other sites More sharing options...
Skye Posted December 10, 2003 Share Posted December 10, 2003 I think DutchE means when it stopped spinning relative to us. From this site: "The Earth's rotation carries the Earth's bulges slightly ahead of the point directly beneath the Moon. This means that the force between the Earth and the Moon is not exactly along the line between their centers producing a torque on the Earth and an accelerating force on the Moon. This causes a net transfer of rotational energy from the Earth to the Moon, slowing down the Earth's rotation by about 1.5 milliseconds/century and raising the Moon into a higher orbit by about 3.8 centimeters per year. (The opposite effect happens to satellites with unusual orbits such as Phobos and Triton). The asymmetric nature of this gravitational interaction is also responsible for the fact that the Moon rotates synchronously, i.e. it is locked in phase with its orbit so that the same side is always facing toward the Earth. Just as the Earth's rotation is now being slowed by the Moon's influence so in the distant past the Moon's rotation was slowed by the action of the Earth, but in that case the effect was much stronger. When the Moon's rotation rate was slowed to match its orbital period (such that the bulge always faced toward the Earth) there was no longer an off-center torque on the Moon and a stable situation was achieved. The same thing has happened to most of the other satellites in the solar system. Eventually, the Earth's rotation will be slowed to match the Moon's period, too, as is the case with Pluto and Charon." I guess the moon has always been rotating at around the same rate relative to earth. [edited to include the italicy bits] Link to comment Share on other sites More sharing options...
blike Posted December 10, 2003 Share Posted December 10, 2003 Sayonara³ said in post #5 :Isn't it the tides that are lunarly locked? It made me laugh. The moon has tides too. The term "tidally locked" is commonly used for a body that has the same rotation as its orbital period. Apparently, many bodies in the solar system are "tidally locked". See: http://www.faqs.org/faqs/astronomy/faq/part5/section-20.html Eventually, both the earth and the moon will be "tidally locked", and the moon will be locked in one position in the sky. As to the original question, I will see if I can find something for you on google. Link to comment Share on other sites More sharing options...
DutchE Posted December 10, 2003 Author Share Posted December 10, 2003 : : "The Earth's rotation carries the Earth's bulges slightly ahead of the point directly beneath the Moon. the gravitational explination would call for the bulge to be pointing at the moon, but i don't think it does. i got a tidal predictor and looked at the tide of a place on the meridian line at midnight at a time of full moon. the moon didn't point at high tide but low tide. therefore, i don't believe in the gravitational model for tides Link to comment Share on other sites More sharing options...
Cheetah Posted December 10, 2003 Share Posted December 10, 2003 So are all moons locked to the celestial body they orbit? So that one side is always turned against the planet? On my second thought. That can't be true, as wouldn't the planets orbiting the sun also only show one side against the sun at all times? Link to comment Share on other sites More sharing options...
blike Posted December 10, 2003 Share Posted December 10, 2003 No, not all bodies are. It depends on how long they've been in orbit. Eventually, the earth will orient toward the sun (assuming its around long enough). Link to comment Share on other sites More sharing options...
VendingMenace Posted December 10, 2003 Share Posted December 10, 2003 actually, the tidal forces the moon exerts on the earth are stronger than the ones the sun exerts on the earth. So first, the erath will stop spinning with respect to the sun (ie. same side of eart will always face the sun. Then, eventually, both the moon and the earth will be titally locked to the sun, with the earth and moon always in the same position to the sun (and at the same time in the same position to themselves). But that will take awhile to happen, so don't worry about buying up all the good real estate yet Link to comment Share on other sites More sharing options...
jordan Posted December 10, 2003 Share Posted December 10, 2003 Since it has been established that time will cause "tidal locks", what is it that would cause this to happen? Link to comment Share on other sites More sharing options...
blike Posted December 10, 2003 Share Posted December 10, 2003 take a look at some of the links above. they explain the effect quite well. Link to comment Share on other sites More sharing options...
Sayonara Posted December 11, 2003 Share Posted December 11, 2003 blike said in post #8 :The moon has tides too... etc sayonara said in post #5 :It made me laugh n/m Link to comment Share on other sites More sharing options...
apollo2011 Posted December 12, 2003 Share Posted December 12, 2003 I believe the correct term is "Synchronous" the moon is moving in synchronous to us so we only see one side. The other side is known as the dark side just because we never see it. It still gets light though. Link to comment Share on other sites More sharing options...
aman Posted December 13, 2003 Share Posted December 13, 2003 If we sped up the moons spin so its rotation reached near its escape velocity, then we could easily land on it and take off using hardly any fuel since we'd be weightless at the equator. Also mining would be simpler. We just need to wind a big cable around the equator like a toy top and anchor it to a passing asteroid. Pull that string and watch that moon spin. Just aman Link to comment Share on other sites More sharing options...
apollo2011 Posted December 13, 2003 Share Posted December 13, 2003 Nice idea aman. That would really be a sight to see! Link to comment Share on other sites More sharing options...
Dave Posted December 13, 2003 Share Posted December 13, 2003 And somewhat of an engineering feat, be quite interesting to watch though Link to comment Share on other sites More sharing options...
apollo2011 Posted December 14, 2003 Share Posted December 14, 2003 And we could probably see it from here too. Link to comment Share on other sites More sharing options...
Sayonara Posted December 14, 2003 Share Posted December 14, 2003 Yes, we could appreciate mankind's mighty control over every force of nature whilst... OH MY GOD IT'S COMING RIGHT FOR US! Link to comment Share on other sites More sharing options...
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