(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?

Pluto was discovered at Lowell Observatory in Flagstaff, Arizona in 1930 and was considered our ninth planet until 2006. The International Astronomical Union reclassified Pluto as a dwarf planet ...

“New Horizons shattered a major paradigm of planetary science,” says Alan Stern, the mission’s principal investigator. “Pluto turns out to have as much complexity as Mars or Earth, so much so that I ...

Images and data have been flowing in since NASA's epic New Horizons Pluto flyby on Tuesday morning, and the latest image released shows an exaggerated color map of Pluto and its moon Charon.

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 ...