Basically for new writers who write a science fiction time travel story you gotta make sure you mention briefly that you solved the orbit/rotation/surface problem and have calibrated your time machine to account for the ever changing topography of the Earth as well as its orbit and rotation
Got to make sure? Why? It's fiction, it's a story, entertainment. If you have to make plausible claims and explaination for every little details it'll be a book that bore you to death.
On a paper submitted by a physicist colleague: "This isn't right. This isn't even wrong." -- Wolfgang Pauli