“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 ...

Clyde Tombaugh discovered Pluto in 1930 at Lowell Observatory in Flagstaff. Here's how Pluto won - and lost - its planetary ...

However, some scientists argue that Pluto should be considered a planet based on geological activity rather than orbital mechanics. NASA’s New Horizons mission revealed ice mountains ...