One Giant Planet X or Actions of Little Worlds?
The outer solar system is a mysterious place. No, it isn’t filled with monsters and ghosts. Not that kind of mysterious. Instead, it’s a mystery because we haven’t explored even a tiny percentage of it. Sure, the New Horizons spacecraft is heading out through it and has explored Pluto. But, it’s one tiny spacecraft and space is very big. There ARE worlds out there, as we know from previous ground-based discoveries of Sedna, Eris, Quaoar, and so on. And, there have been hints of something big out there—really big. Is it a large world? Or could it be something else?
Gravity tells a Tale of Sedna’s Orbit
An artist’s conception of Sedna, a dwarf planet in the Kuiper Belt. Credit: NASA/JPL-Caltech
The main way we “know” something is out there is because there’s a gravitational perturbation affecting the known worlds in the Kuiper Belt. Whatever it is, it’s causing those orbits to change a tiny bit, and that’s measurable by telescopes here on Earth. Planetary scientist Mike Brown of CalTech suggested that it’s a big Planet X, some monster world with enough mass and gravity to tug on orbits of smaller ...