Astronomers say there could be at least 2 more mystery planets in our Solar System. If you were still getting your head around the concept of the mysterious Planet Nine potentially tracing its elusive orbit somewhere around the fringe of the Solar System, try this on for size. A team of astronomers has performed new calculations on the data that originally gave rise to the Planet Nine hypothesis, and these new numbers suggest that the hypothetical extra planet might not be alone – there could be multiple planets hiding at the edge of our Solar System that we've yet to discover. If the researchers are correct – which nobody knows for sure right now – it could really mean a do-over for the high school textbooks. But first, let's backtrack a little to explain how we got to this point. In January, researchers from the California Institute of Technology (Caltech) found evidence for what they call Planet Nine, a huge icy planet that could be lurking somewhere beyond Neptune in the far