You can google that question but be ready for an all out nerd war.
From what I've read, in the extended universe, there is some reference to Han and Chewie landing on Earth in the 1800's where Han is shot by indians, dies and whose bones are later found by Indiana Jones and Short Round who were searching for Big Foot, AKA Chewbacca. Seriously. I'm not making that up.
There was also a reference to the E.T race in the Star Wars universe who had supposedly sent an expedition outside their galaxy, presumably to Earth. In the E.T film he indicates that his home world is about 3 million light years from Earth which puts it in range of the Andromeda Galaxy. There was also a nod to Yoda in the the E. T. film, if you recall. The E. T. time is hard to calculate since nobody can agree on how fast their ship traveled or if it really was Earth that they were referring to.
At this point my head exploded.