It might be another 1,000 years before we can see the elusive 'Planet Nine'

"Planet Nine," the mythical hidden planet that may or may not be lurking in the very distant reaches of our Solar System, continues to avoid detection by astronomers. It's like the Loch Ness Monster of planets -- it might exist, or it might not, but scientists think they have evidence that something is out there. But if we've found eight (and a half) of the planets in our system already, what is making it so difficult to close the book on the ninth? Well, it's complicated, but it has a lot to do...