XPost: rec.arts.sf.science   
   From: max@alcyone.com   
      
   Brian Davis wrote:   
      
   >    Yep. That's why it's called *conservation* of angular momentum   
   > . The Earth precesses because it has a torque on it, a   
   > gravitational torque from the Sun & Moon (these dominate) and other   
   > planets (OK, it takes two things: the Earth has to have a "handle" of   
   > some sort as well, such as the equatorial bulge due to it's rotation).   
   > To get a faster precession, reduce the angular momentum or increase   
   > the torques. But to push it to a year... well, I'd have to do crunch   
   > the numbers. I'm certain you couldn't do it gravitationally, but you   
   > might be able to do it via light pressure or mass exchange   
   > (import/export) from the habitat.   
      
   The precession angular velocity is equal to the ratio of the torque to   
   the angular momentum.  To increase the precession rate from 2 pi/(26 000   
   yr) to 2 pi/(1 yr) is of course an increase in the angular velocity of   
   26 000, so you'd have to increase the torque/angular momentum ratio by   
   26 000 to get the precession rate up that fast.   
      
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    __ Erik Max Francis && max@alcyone.com && http://www.alcyone.com/max/   
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