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 ...

Pluto sits far out in the Solar System, small and dim, moving at a pace that barely fits human timelines. It was found in ...

Pluto's days, though they drag on a bit at around 153 hours, are nothing compared to its years. Pluto's orbit takes 248 Earth ...

What was discovered in Flagstaff, Arizona, and killed off in Prague? If you answered "Pluto's planethood," your grasp of the astronomical is excellent. Feb. 18 marks the 95th anniversary of the ...

Pluto, discovered in 1930, was once considered the ninth planet in our solar system. In 2006, the International Astronomical Union reclassified Pluto as a dwarf planet because it doesn't meet all the ...

Frankly, we don’t keep up much with Pluto and its status as a planet or non-planet. It’s kind of like when, as a young altar boy, the Catholic Church demoted a bunch of saints. We just rolled with the ...

For the first time since Pluto was demoted, the idea of a true ninth planet is edging from speculation toward something testable. Instead of restoring Pluto, researchers are closing in on a different, ...

1. What is a planet? -- 2. Seven perfect planets made of aether -- 3. The Earth becomes a planet -- 4. Sixteen planets -- 5. Not everything that orbits the Sun is a planet -- 6. Uranus! -- 7. The ...

(Correction: An earlier version of this story misstated how far Pluto is from the sun. The correct number is 3.7 billion miles.) What was discovered in Flagstaff, Arizona, and killed off in Prague? If ...