Some 5 or 6 or 7 billion years from now, the Sun will become a red giant star and will engulf the orbits of Mercury and Venus and probably the Earth. The Earth then would be inside the Sun, and some of the problems that face us on this particular day will appear, by comparison, modest. On the other hand, since it is 5,000 or more million years away, it is not our most pressing problem. But it is something to bear in mind. It has theological implications.
Carl Sagan, the Varieties of Scientific Experience