> Though even if we do manage to alter the orbit I think it can be done by diverting a very large asteroid or series of asteroids to pass close by the Earth re

> Though even if we do manage to alter the orbit I think it can be done by diverting a very large asteroid or series of asteroids to pass close by the Earth repeatedly, using their gravity to gradually change Earth's orbit. 200 million years gives us enough time to do so.