There's a growing consensus among astronomers that beyond the gas giants of the outer solar system lurks a mysterious object — perhaps a black hole — influencing the massive cloud of small, icy bodies in the Oort cloud.
And it turns out there is some evidence to suggest this hypothesis might be right. No one is sure how a planet massive enough to affect the cloud of icy leftovers from the solar system's birth could form at such a great distance from the sun. "All we know is that there's an object of a certain mass out there," said Theorist Jakub Scholtz of the U.K.'s Durham University, in a