Plot from wikipedia:
"In the future, the Sun has aged and is about to turn into a red giant, pushing the nations of the world to consolidate into the United Earth Government, a world government, to initiate a project to move the Earth out of the Solar System to the Alpha Centauri system....."
That's just too far fetched for me. I like my sci-fi to be a bit more "sci" and a little less "fi".