A New Planet? The Kuiper Belt, Jupiter Rising, and More Zombies!!!

Ninth Planet? A decade ago Mike Brown helped get Pluto demoted from a “planet” to a mere “dwarf planet.” Now the astronomer and one of his CalTech colleagues may have plotted the orbit of a new ninth planet in our solar system, dramatically larger than Pluto and much, much farther away in the Kuiper Belt. 
This new planet would be roughly 10 times the size of the Earth and would take as much as 20,000 years to make a single orbit around the sun. Its theoretical size — between the size of...