In 1930, scientists discovered a small celestial body on the outer edge of our solar system. They called it Pluto and classified it as a planet. However, the International Astronomical Union (IAU) — ...

Once the quirky underdog of our solar system, Pluto held planetary status until 2006, when it got a cosmic demotion that still stings space fans. Discovered in 1930, Pluto was the ninth planet for ...

Before Pluto was discovered, it was predicted. Astronomers had observed that massive objects can affect the orbits of their neighbors and, after seeing deviations in the orbits of Uranus and Neptune, ...

When the International Astronomical Union (IAU) demoted Pluto from a planet to a dwarf planet in 2006, it surprised a lot of people, including some scientists. Even many years later, some astronomers ...