The heart's brightness arises from sunlight reflection, while red patches, formed by tholins, showcase Pluto's atmospheric ...

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 ...

(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 ...

Aug. 15, 2006 — -- When Clyde Tombaugh discovered Pluto in 1930, he made a mess of the solar system. Pluto was too small, too distant, and of the wrong makeup to qualify as a planet, many ...

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 ...