ammonia-bearing species and organic materials responsible for its gray and red coloration." Related: Pluto's huge white ...

(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?

Since its discovery in 1978, Pluto's largest moon ... and organic materials responsible for its gray and red coloration." ...

This story appears in the July 2015 issue of National Geographic magazine. Small, cold, and absurdly far away, Pluto has always been selfish with its secrets. Since its discovery in 1930 ...

Pluto is too far away from Earth to be seen with the naked eye. If you stood on Pluto's surface, the Sun would merely appear to be a very bright star. Although previous images showed that ...

A blue atmosphere, smooth areas, and youthful mountain ranges - this dwarf planet is full of surprises. When NASA's New Horizons probe flew past Pluto in July 2015, the images it returned astonished ...

Pluto was discovered 95 years ago on Feb. 18, and even though it was demoted nearly two decades ago, it remains a fascinating part of our solar system. "Pluto is a complex and mysterious world ...

NASA's New Horizons spacecraft conducted the first and only flyby of the Pluto system, culminating at the closest approach of that distant world in July 2015. Sailing onward, the probe carried out ...