The secret to all of that activity is Pluto’s probable underground ocean. The water ice on the surface of the world suggests that there should be more water hidden below ground. Over the course ...

But instead of surface water being evaporated by the Sun and falling as rain, Pluto experiences a daily nitrogen cycle. Nitrogen is heated and cooled as Pluto rotates. A New Horizons image of ...

Instead of a barren ice ball, Pluto featured vast plains of nitrogen ice, jagged mountains made of water ice, and intricate networks of frozen canyons. Its heart-shaped region, informally called ...

open image in gallery Pluto was once our solar system's ninth ... Notably, they are generated by molecules that contain water and feature carbon dioxide ice, and silicate-rich dust.