[Ethan Clive Osgoode]

But if the earth is fixed and the sun is orbiting the earth

Fixed by what? I thought you said there were no third bodies. And what is it that propels the Sun around the Earth in a circular orbit at 11,000 km/s? There must be some kind of supposition behind that. Is it magic?

[LeGrande]

Fixed by what? I thought you said there were no third bodies. And what is it that propels the Sun around the Earth in a circular orbit at 11,000 km/s? There must be some kind of supposition behind that. Is it magic?

I take it you have never heard of a thought experiment. Did you read this quotation that fichori requested?

http://www.mathpages.com/home/kmath249/kmath249.htm

"and therefore the Earth's gravitational acceleration should always point directly toward the Sun's position at the present instant, rather than (say) the Sun's position eight minutes ago."