In Search of Planet 9

Proposed mockup of our solar system (the sun is the tiny yellow dot in the middle), and the proposed orbit of Planet 9 (called Planet X here). (Courtesy of Scott Sheppard / Carnegie Institution of Washington) An Orbital Path episode all about…an orbital path! Planet 9’s, to be exact. The replacement for Pluto as our solar system’s ninth planet is out there somewhere, and astronomers can see the ripples it creates, especially at this time of year. In this Episode: On November 5, 2012, astronomer Scott Sheppard and his team discovered a small, frozen space rock at the edge of what we’re able to observe in our solar system. He never anticipated that this observation would hint toward a big change in how we understand solar system: the existence of an undiscovered planet inside our solar system. Astronomer Mike Brown, better known for “killing Pluto,” is leading the hunt for Planet Nine and he thinks that we won’t have to wait for much longer.