I never considered this aspect of the challenge of time travel..
If you count rotation, revolution, galactic, super-galactic, and CBR motions we’re moving somewhere on the order of 850,000 m/s through space (and the rotation/revolution/galactic motions are almost negligible).
If you cannot instantly travel through space at the same time as you travel through time you will most likely land either in solid rock or far, far out in deep-space somewhere; unless you limit it to a few microseconds.
If you wanted to jump back 100 years, you would have to travel some 1.7 trillion miles to be in the vicinity of the Earth at that time. And that assumes you can send a whole spaceship back – if you can only send a human you would have to make that calculation to a phenomenal positioning accuracy in space so you could plop down on your couch (or whatever).
(Via www.quora.com)