So I've never studied physics before, but my friend showed me the results from the Hafele-Keating Experiment. It states that a plane-bound clock flying eastbound (with the earth's rotation) experiences time dilation and thus returns to us slower than a ground-based clock (and thus loses time). I get that. But it also shows that a plane-bound clock flying WESTBOUND (against the earth's rotation) experiences time contraction and returns to us FASTER than a ground-based clock (and thus gains time). I honestly have no idea why the westbound clock is different. Isn't it still moving relative to the ground-based clock, regardless of its direction of motion? Doesn't it experience time dilation all the same? Why is it different? Any physics buffs have any idea? I'm really at wits end with this... been thinking about it all week.