> They must teach things different on the other side of the planet. I've not > heard that before. Well, they do have a different view of the solar system over there ;) Anyway, Enrico is right, and so am I. This page says it all: http://csep10.phys.utk.edu/astr161/lect/solarsys/binary.html Basically, most systems are binary, but any binary system is unlikely to have habitable planets. Also, if Jupiter had been bigger, it would have becomes a star and we wouldn't exist! Darryl