Is Pluto Really A Planet? Scientists to Decide

The International Astronomical Union (IAU) hopes to settle the question of Pluto, which was first spotted in 1930.
Experts are divided over whether Pluto - further away and considerably smaller than the eight other planets in our Solar System - deserves the title.

The stakes were raised when a bigger planet-type body, known as 2003 UB313, was discovered by a US astronomer. Any decision to downgrade Pluto would send shockwaves through the scientific community, instantly outdate textbooks, and change how the basics of the Solar System are taught in schools. - bbc