Rob Seaman said: > > Would the earth be slowing down so fast without the moon? There's some > > tidal coupling in the earth-sun system but isn't it much smaller? > > Wonderful questions. I'll bet there are lurkers here who could speak > authoritatively :-)
There is no way that I can speak authoritatively about this. But I took some numbers from the Williams paper that was cited and played with them in a spreadsheet. These suggest that about 90% of the terrestrial rotational angular momentum reappears as lunar orbital angular momentum. On the other hand, I can't see where the rest of it would go - apparently observations show no indication that the Earth's orbit is growing. > The tides themselves are only a means to an end mediating the transfer of > terrestrial rotational angular momentum to lunar orbital angular momentum. > The efficiency of this is presumably an "interesting" (and perpetually > varying) combination of many factors, It's suggested in my reading that the present period has an abnormally high transfer rate because of the present arrangement of the continents and, therefore, the oceanic tides. Certainly the present rate cannot have happened for long periods - projecting back they make the moon collide with the earth about 1 to 2 Gyr ago. > Tides are an inverse-cube effect suggesting that the coupling was stronger in > past aeons since the Moon was closer. The deceleration ought be decelerating > in a smoothed long-term trend. That's not what the numbers appear to show. -- Clive D.W. Feather | If you lie to the compiler, Email: cl...@davros.org | it will get its revenge. Web: http://www.davros.org | - Henry Spencer Mobile: +44 7973 377646 _______________________________________________ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs