Someone once conducted an experiment in which the subjects were fitted with eyewear that turned their view of the world upside down. Eventually, they got used to it and everything was "normal." But once they took the eyewear off, they had to go through the adjustment all over again.
This would bring a whole lot of changes given that one has to land somewhere. Therefore, it would mean that everyone would be floating around and there would be no vegetation. When compiling all the aspects and possibilities, the thought would be quite to figure out.