You have to sit with the Michelson and Morley experiment for a bit to really see how it's supposed to work, because it's a little bit inobvious.
Once you see how that's working, then if you imagine an electron going around in an orbit - if (we conjecture) that electron's speed is actually a fixed number relative to C, and furthermore we imagine that Michelson and Morley were right and there IS an aether, then you can infer that the forward/back part of the electron's orbit will be faster than the right/left part (with forward defined in terms of the direction of travel of the moving body in the aether)
