This new theory helps explain the large, 1,600-kilometer-wide heart-shaped area on Pluto's surface covered by a thick layer of nitrogen ice, which has intrigued scientists since its discovery by ...

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?