The science corner of the Internet is buzzing with news of a newly discovered planet. Billions of miles beyond Neptune, there is likely a ninth planet of significant size within our solar system, one that is most definitely not Pluto. No one, however, has seen it. We do not yet have the technology to see anything at such a distance. So how can astronomers claim the planet is out there? The same way that astronomers have done for thousands of years: by watching the collective movement of other objects surrounding the area where the new planet is assumed to be.