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Re: Retrograde Motion - Virtual Particles



On Tue, 25 Jun 1996, Jim Green wrote:
...
Here is the problem: I see that as my fast car passes a slower car on the
interstate, the slower car seems to reverse direction just as I pass. BUT
that car never seems to reverse again to go forward.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Yes it does -- as soon as you are far enough ahead of the slower car it
will once again be seen to be moving forward against the distant background,
just as the planets do. Try drawing lines from faster car through slower
car to distant background at various stages of the motion and look at the
figure traced out at the distant background. It will be a retrograde loop,
ending up going forward again.

But Mars, etc *do* -- somebody help me out here!!!! Please!

Most astronomy texts spend a little time plotting out the situation and
showing how the apparent planetary motion is exactly similar to the
mundane faster-passing-slower situation. Try looking there.

Maybe Tycho was right.

Jim Green

A. R. Marlow E-MAIL: marlow@beta.loyno.edu
Department of Physics PHONE: (504) 865 3647 (Office)
Loyola University 865 2245 (Home)
New Orleans, LA 70118 FAX: (504) 865 2453