We're twins, and we didn't even know it! From Science Blog:
The Binary Research Institute (BRI) has found that orbital characteristics of the recently discovered planetoid, "Sedna", demonstrate the possibility that our sun might be part of a binary star system. A binary star system consists of two stars gravitationally bound orbiting a common center of mass. Once thought to be highly unusual, such systems are now considered to be common in the Milky Way galaxy.
Walter Cruttenden at BRI, Professor Richard Muller at UC Berkeley, Dr. Daniel Whitmire of the University of Louisiana, amongst several others, have long speculated on the possibility that our sun might have an as yet undiscovered companion. Most of the evidence has been statistical rather than physical. The recent discovery of Sedna, a small planet like object first detected by Cal Tech astronomer Dr. Michael Brown, provides what could be indirect physical evidence of a solar companion. Matching the recent findings by Dr. Brown, showing that Sedna moves in a highly unusual elliptical orbit, Cruttenden has determined that Sedna moves in resonance with previously published orbital data for a hypothetical companion star.
What's the Binary Research Institute? It's a scientific research organization based in Newport Beach "formed in 2001 to support and fund research regarding the hypothesis that the Sun is part of a binary star system. It is the goal of the Binary Research Institute to present evidence for this theory, showing that the motion of the sun along a binary orbital path can result in and better explain" various phenomena such as the Earth's wobbling rotation, and help us understand the movement of our solar system through the Milky Way.
Its founder is Walter W. Cruttenden, a private investor, amateur astronomer and archeoastronomer. (I must admit, his organization's name makes me a little suspicious. It's one thing to begin a scientific inquiry with a hypothesis, but if I founded the "Life on Mars Institute," wouldn't that insert bias into the whole enterprise? Just asking.)
If our Sun has a partner, shouldn't we be able to see it? Not necessarily. According to the Institute,
there could be a dark binary, such as a brown dwarf or possibly a relatively small black hole, either of which might be very difficult to detect, without accurate and lengthy analysis.
Beyond direct detection – one way to determine if we are in a binary system is to see if the Sun is curving through space. To us on Earth that means we should experience a gradual “changing orientation to inertial space.” Such a phenomenon is observed as the precession of the equinox.
Precession of the equinox refers to the fact that the stars are fixed, but over a 25,800-year period, their position in the sky relative to Earth completes a cycle. Lots of guesses as to why, but no firm findings. The Institute believes our Sun's secret friend might explain it.
If this hypothesis is true, it would be big news to us, but it wouldn't be all that remarkable. Many easily observable stars are part of binary systems. Our partner might be very far away, completing a distant orbit — a dancer on the other side of the ballroom. And, as suggested above, it might not be visible. Black holes don't emit light, and brown dwarves cannot sustain nuclear fusion and thus burn only dimly.
Being followed by something big that we can't see…a paranoia-inducing concept! Somehow I'm reminded of my misspent youth, when police cars sometimes followed my pals and me in the wee hours with their lights off, only to reveal themselves at the last minute to determine if we were up to no good. (Fortunately, we were all choirboys, pure at heart.)