connected.telegraph.co.uk - Does the Sun have a doomsday twin?

"Under their original theory, called the Nemesis theory, this small dark star, which lurks at around 90,000 times farther away than the Earth is from the Sun, may be on an orbit that, once every 30 million years, ploughs it into the densely packed inner cloud. Here its immense gravitational pull would drag out several of the Oort comets and give them the "kick" needed to send them towards the Sun on orbits perilously close to the Earth. This explains, in the professor's view, the ominous mass extinction cycle, due to regular periods of increased cometary activity every 30 million years."