Is 'Planet 9' Really a Second Massive Kuiper Belt?

The Kuiper Belt is a massive collection of dwarf planet- and asteroid-sized worlds orbiting far past Neptune. Is the hypothetical Planet 9 really a second such belt? Image Credit: T. Pyle (SSC)/JPL-Caltech/NASA

The announcement of a possible large ninth planet in our Solar System way beyond Neptune last month caused a lot of […]