Re: ZetaTalk and Spaceguard UK

Bill Nelson wrote:
> The planets are NOT "pulled inward" or "pulled outward".
> The gravitational attraction of the Sun is too great to allow
> that. What happens is that the planets change their orbital
> velocities slightly. This causes the orbit to move inward and
> outward - with the net change in orbital radius being zero.

I can see that it might be hard to pull a weighty planet OUT away from
the Sun, by this logic, but how about a perturbation that might pull a
weighty planet IN toward the Sun.  Why would this not happen?  Saturn
passes Jupiter which is closer in.  The perturbations only affect its
speed within its same orbit, NOT a draw in toward both Jupiter and the
Sun?  Why not?