Like the icebergs that float in Earth's Arctic Ocean, it seems Pluto has water ice "hills" that float atop an ocean of frozen nitrogen.
PHOTOS: Dive Onto Pluto's High-Resolution Landscape
In new images beamed back from NASA's New Horizons mission, which zipped past the dwarf planet on July 14, 2015, glorious detail has been added to Pluto's famous Sputnik Planum, the western half of the heart-shaped Tombaugh Regio feature. Planetary scientists are still poring over the observations, but they've made some interesting early discoveries as to the surprising dynamics underway in Pluto's ice.
Sputnik Planum is known to contain large quantities of nitrogen ice, giving the region a smooth appearance against a "shoreline" of craggy mountains. But just because it's ice, it doesn't mean it's static. The physics of ices in the outer solar system is very different to what we're used to on Earth. This ocean of nitrogen is in motion, albeit extremely slowly. Over millions of years it is believed the ices in Sputnik Planum are cycling - akin to a retro lava lamp - creating a complex pattern of convection cells.
PHOTO: A ‘Wright Mons-ter': Pluto's Ice Volcano Is Huge
Amidst the "high seas" of nitrogen ice, huge chunks of water ice have been spotted. As water ice is more buoyant than nitrogen ice, the water ice floats in a not-so-unfamiliar fashion to icebergs in our oceans. As such, these New Horizons images are showing a migrational pattern of huge hills of water ice being pulled out into "chains" that collect in groups and drift to the nitrogen ice's convection cell edges.
"The hills are likely fragments of the rugged uplands that have broken away and are being carried by the nitrogen glaciers into Sputnik Planum," writes a NASA New Horizons news update.
NEWS: Young at Heart: Pluto's Ice Only 10 Million Years Old
In addition, a large feature toward the north edge of Sputnik Planum is a cluster of water icebergs that have apparently "beached" themselves. After floating atop the nitrogen ice, they've hit a shallower portion, becoming grounded and accumulating. This near-40 mile-wide feature has been called "Challenger Colles" by the New Horizons team, honoring the crew of the Space Shuttle Challenger that exploded shortly after lift off 30 years ago.