Originally Posted by BlueTiger

A couple of months ago The Universe did a feature on the theory that the Sun is part of a binary system. Its partner is a so far undetected red dwarf (or maybe even a brown dwarf) named Nemesis with an extreme eliptical orbit which brings it through the Oort Cloud every 26 million years or so. This causes perturbations in orbits of comets bringing them into the inner solar system to wreck havoc. I'm sure its next close encounter with the solar system will be in 2012.