“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 ...

This cutaway image of Pluto shows a section through the area of Sputnik Planitia, with dark blue representing a subsurface ocean and light blue for the frozen crust. Disclaimer: AAAS and EurekAlert!

NASA sent its probe New Horizons on a flyby in 2015. It confirmed the tiny planet harbored an ocean beneath its thick, icy shell. Pluto was always in a tough spot when it came to being a planet.

The controversy endures over Pluto's true status, but the solar system underdog continues to capture hearts across the globe. Clyde Tombaugh didn't set out to discover Pluto when he sent his ...

If Pluto's ocean had frozen solid, pressure from the heavy outer shell would have squished it into an extremely dense phase called ice II. "This would make Pluto's surface buckle, like the skin of ...

When you buy through links on our articles, Future and its syndication partners may earn a commission. This high-resolution image captured by NASA's New Horizons spacecraft combines blue, red and ...

The heat might be coming from a hidden ocean or radioactive elements beneath Pluto's surface. This would be a real turn-up for the books as, until now, astronomers thought Pluto was too old to ...

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 ...