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 ...

The debate over Pluto’s planetary status has been ongoing since its reclassification as a “dwarf planet” in 2006 by the International Astronomical Union (IAU). Recent discussions and new scientific ...

The planet Neptune wobbled in its orbit around the Sun. That could only mean one thing, astronomers said: There was a ninth planet out there, somewhere, lurking in the fringes of the solar system.

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 James Webb Space Telescope (JWST) has discovered that a hazy sky over frozen Pluto is helping to cool the dwarf planet's atmosphere, while at the same time giving methane and other organic ...