Computer simulations heat up hunt for Planet Nine

For a planet that hasn’t technically been discovered yet, Planet Nine is generating a lot of buzz. Astronomers have not actually found a new planet orbiting the sun, but some remote icy bodies are dropping tantalizing clues about a giant orb lurking in the fringes of the solar system.

Six hunks of ice in the debris field beyond Neptune travel on orbits that are aligned with one another, Caltech planetary scientists Konstantin Batygin and Mike Brown report (SN Online: 1/20/16). Gravitational tugs from the known planets should have twisted the orbits around by now. But computer simulations suggest the continuing alignment could be explained by the effects from a planet roughly 10 times as massive as Earth that comes no closer to the sun than about 30 billion kilometers — 200