DailyDirt: My Very Educated Mother Just Served Us Nine...
Techdirt. 2016-01-25
Summary:
If you're young enough, you were only taught about the eight planets in our solar system -- and possibly that there was a mysterious 'Planet X' or planet Tyche beyond Neptune. More recently, there's a new ninth planet proposal from the same folks who re-named Pluto as a dwarf planet. Check out these links on Pluto and this new ninth planet that might redefine the outer edge of our solar system. 
- Twisting the knife into Pluto, Michael Brown and his fellow Caltech astronomer Konstantin Batygin have proposed a ninth planet in our solar system -- that's about the same size as Neptune but with an orbit so large that it would take roughly 15,000 earth-years to complete its own journey around the sun. What does Brown have against Pluto? Dwarf planets are still cute, I suppose. [url]
- Pluto was discovered in 1930, and at the time, it was mistakenly thought to be about the same size as the Earth. Further measurements revealed that Pluto is actually about 0.2% as massive as the Earth -- and that similarly-sized bodies in space called 'trans-Neptunian objects' (TNOs) also existed in our solar system. Since the discovery of TNO Eris in 2005 meant that Pluto was less planet-like than previously thought, these larger TNOs were named dwarf planets -- and Pluto was demoted. (And Pluto still hasn't even finished its 248-year-long orbit around the sun since it was discovered as a 'planet'... before it was re-classified as not a planet.) [url]
- Despite its dwarf planet status, Pluto has five moons of its own. Seriously. Five. Charon, Styx, Nix, Kerberos, and Hydra are the names of Pluto's satellites, and Charon is about half the size of Pluto -- which had some astronomers proposing to call Pluto a binary planet or double planet (binary dwarf planet?). [url]