It’s official, Pluto is no longer a full-fledged planet. The new definition finalized by the International Astronomical Union today states that a planet in “a celestial body that (a) is in orbit around the Sun [or another star], (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit.” Pluto does not meet the third requirement, so will now be a dwarf planet along with Ceres and 2003 UB313 (aka Xena) plus some others.
Personally, I have thought this should be the case for a while now. Since we keep finding Pluto-like bodies out there, it’s hard to see Pluto being more “important” than all these other (even though it may be a bit bigger).
So go rewrite your textbooks… how do you like “Noodles” replacing “Nine Pizzas”?