Is Pluto a planet? Here's what changed to make it a dwarf planet. - USA TODAY

Pluto is classified as a dwarf planet because it doesn't fit into the internationally recognized definition of a planet.
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Subject to memorization in school and known as the definitive planetary lineup, Pluto was included in the list until the Inter… [+3585 chars] Read More