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 ...

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 ...

Scientists who argue for Pluto to be classified as a planet are getting more ammo for a debate that has raged over the last 15 years. A team of researchers published a study in the scientific journal ...

A new formation theory for Pluto's moon Charon could explain why Pluto is geologically active. Illustration incorporates NASA New Horizons terrain imagery. Pluto — demoted to dwarf planets status in ...

We are less than two weeks away from the 95th anniversary of the discovery of Pluto, the ice-caked, rocky sphere orbiting ...

It's going on two years since the International Astronomical Union rewrote its definition of a planet and busted Pluto down to something it called a "dwarf planet." But it's not a done deal, says Mark ...

The director of the American Museum of Natural History's Hayden Planetarium and author of The Pluto Files, Neil deGrasse Tyson, talks about the... Astrophysicist Tyson On 'Pluto Files' The director of ...

FLAGSTAFF, Ariz. It's been 75 years since the discovery of Pluto, but it remains a mystery. Perhaps in another 10 years some of its secrets will be revealed when a space probe gets close enough for a ...

The planet in the cornfield -- Fellow wanderers -- The search for planet X -- Pluto and its little pals -- The meaning of a moon -- There goes the neighborhood -- Not yet explored -- Betting on 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 ...