There’s Flowing Ice on Pluto

Glaciers of nitrogen flow out of Pluto’s heart, Alex Witze reports for Nature. The research team behind NASA’s New Horizons mission announced the finding and other new information about the dwarf planet’s atmosphere and surface environment on July 24.

Soon after the probe’s historic flyby, New Horizons began sending back information about Pluto’s unique geology — evidence of mountains, craters and a heart-shaped terrain feature that’s been dubbed the Tombaugh Regio (for Pluto’s discoverer Clyde Tombaugh). New Horizons data suggests that nitrogen, carbon monoxide, and methane ice fills the area. This may serve as a reservoir for the gases that comprise the planet’s atmosphere and other aspects of its geology, explains Ashley Yeager for Science News.

Before zipping off to explore the outskirts of our solar system, the probe captured an image of Pluto’s hazy atmosphere backlit by the sun. The haze could be due to ultraviolet light from the sun breaking down gases in the outer atmosphere, causing them to fall to the colder lower atmosphere and snow onto the planet’s surface.

Scientists also spotted ice flowing out of cratered valleys into frozen plains called the Sputnik Planum, near the Tombaugh Regio. Pluto is really, really cold, writes Witze — too cold for watery ice flows. However, nitrogen could flow on the planet’s cold surface, with help from the heat generated from radioactive decay seeping up from Pluto’s innards.

If Pluto has flowing ice, it might also have an underground ocean, Yeager points out. Since 2011, astronomers have theorized that Pluto might harbor a sea beneath its surface. Slow-moving ice on the surface could trap heat inside the dwarf planet, keeping things warm enough for a sea of water and nitrogen to form. But for now, Pluto’s underground ocean remains a theory — one that only further study can confirm.

Watch a simulated flyover of the Sputnik Planum and a mountain range called the Hillary Montes below:

Flying over Pluto's icy plains and Hillary Mountains

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Helen Thompson | | READ MORE

Helen Thompson writes about science and culture for Smithsonian. She's previously written for NPR, National Geographic News, Nature and others.