One Pluto year equals 248 Earth years. At 1473 miles in diameter—about half the width of the United States—Pluto is the ...

Astronomers have discovered a mysterious dwarf planet, 2017 OF201, far beyond Pluto. This discovery challenges existing ...

Although telescopes from Earth detected gases on Pluto in 1988, researchers surmised that the tiny planet was losing them too quickly to build up a permanent layer in its skies. But when New ...

(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?

song, Interplanet Janet. Upon the discovery of its existence in 1930, Pluto enjoyed decades of special status as one of the solar system's planets. Then, in the summer of 2006, Pluto was demoted.