The Sun’s evil twin.

No, I’m not referring to the British Newspaper “The Sun” but to the star that gives us all the light of day.  That big, bright, shiny yellow thing in the sky.  Does the Sun have an evil twin?  Well, there’s a scientific theory that seems to say so.

Nemesis, is a hypothetical, hard to detect red dwarf star, or possibly a white dwarf (unlikely) or brown dwarf (possible) that is orbiting the sun every 26 million years (yep that is million and not a typo).  Its distance from the sun is about one and a half light years beyond the Oort cloud (no this isn’t a typo either).  The Oort cloud is all the frozen rocky, dirty snowball stuff that makes up the core of a comet.

It is believed that as Nemesis heads in toward the sun it knocks bits of the Oort cloud out of place sending it in toward the sun – and us!  This is why it is thought that the earth faces mass extinctions every 26 million years or so (or whatever), the earth get’s a smack by a comet knocked out of its safe orbit by the Sun’s evil twin.

Nemesis is only a fraction the mass of the Sun (which is why it’s a dwarf) and no where near as bright (white, red or brown in color) and impossible to see from the earth by any telescope – but not in the infrared spectrum from space which is why there’s a satellite up there looking for the little bugger.

David Raup and Jack Sepkoski identified in a paper a statistical periodicity in extinction rates over the last 250 million years.  They found what they believed to be a pattern of extinctions on average of every 26 million years but they could not identify a cause.  This later drew the attention of several teams of Astronomers, leading to the hypothetical Nemesis.  Don’t hold your breath!  In 2010 Melott and Bambach re-examined the fossil data using improved dating and found evidence suggesting an extinction rate of 27 million years.  Given that there’s no sign of the little bugger causing all the problems and we’re still in the ‘safe zone’ I don’t think there’s any need to increase your insurance policy just yet.