Planet 9, the mysterious hypothetical object at the edge of the solar system. What really is it? We’ve been theorizing and collecting evidence about the existence of this mysterious planet ever since the demotion of Pluto. In fact, we have enough evidence that the next step of this mission may be that we find the planet altogether. But what evidence do we have, and how do we have proof? This short project explains some things you need to know about the mysterious Planet 9.
