The Kuiper Belt, which has Pluto as the largest member, is a region of comet-like objects just beyond Neptune. Over the past few years, Dr. Sheppard and his team have been performing the largest and deepest survey ever attempted of our Solar System’s fringes. In December 2018, he announced the most-distant object ever observed in our Solar System. His team’s work has shown that the farthest-out-there objects—beyond the Kuiper Belt and the influence of the known major planets—are strangely grouped together in space. This suggests the existence of a yet-unobserved planet, sometimes called Planet X or Planet 9, more massive than the Earth, which is shaping the current orbits of these objects. Dr. Sheppard will discuss the most-recent discoveries at the edges of our Solar System.