2006:"planet" is defined, and Pluto isn't one

Pluto was discovered in 1930 by American astronomer Clyde Tombaugh. It was regarded as the ninth planet from the sun in our Solar System.

Astronomers later found many similar objects in the outer solar system, and on August 24, 2006 the International Astronomical Union defined the term "planet" for the first time. Their definition excluded Pluto, which was then reclassified under the new category of dwarf planet.

Pluto is smaller than several of the moons in our solar system, and approximately one-fifth the mass of Earth's moon.

Pluto is primarily composed of rock and ice.

Pluto is now classified as the prototype of a family of trans-Neptunian objects.

Walt Disney's Pluto is still classified as a dog.

The American Dialect Society voted “plutoed” as the 2006 word of the year. To pluto is to demote or devalue someone or something, as happened to the former planet Pluto