It isn't visible to the naked eye, and when viewed through a large telescope it looks very much like any of the ordinary cosmic bodies in its celestial neighborhood. But this pinpoint of light is anything but ordinary. Spotted more than three years ago, it seemed at first to be a garden-variety star--but it wasn't. It might have turned out to be an unremarkable galaxy or quasar--but it didn't. Frustrated in their attempts to learn its nature, and even its distance from Earth, astronomers have begun to refer to the mystery object as, well, the "mystery object."
Just what the enigmatic...