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Said LeGrande: Where you are probably confused is in my assertion that in a two body model it makes no difference which body is circling the other or if one body is simply spinning.

The problem is, LeGrande, that you made that assertion regarding the sun, the earth, and light -- and light is a third body! (which you admitted when I told you that a ring laser gyro buried ten feet deep on the earth will be able to tell the difference between the earth rotating and the sun orbiting.) So we're talking about a 3 body model - and you're making an argument based on a 2 body model? What's with that?

The sun's light, once emitted, barring matter or force which changes its course, continues to travel in a straight path, regardless of whether the sun is still where it was at the time or not. So if the sun moved 2.1 degrees, then the light will appear 2.1 degrees lagged by the time it reaches earth. On the other hand, if the sun did not move degrees in 8.3 minutes, then the light will still be coming from the same direction of where the sun is.

So clearly, the sun's light qualifies for the third body in this case!

-Jesse