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A peek inside Pluto's icy heart

Plus a glimpse at the dwarf planet's hazy atmosphere

NASA

NASA's New Horizons spacecraft has found evidence of ice flowing across Pluto's Sputnik Planum region — the large white heart that's roughly the size of Texas. High-resolution pictures taken by the probe show a sheet of ice that has recently moved and may still be moving. NASA researchers say they've only seen this kind of surface activity before on Earth and Mars.

Previous images of Pluto's surface showed icy, frozen plains inside Sputnik Planum; the newest ones also show the ice is moving similarly to how glaciers flow on Earth. That means geological activity occurred recently on Pluto.

The New Horizons team is also using enhanced color photos to get a better understanding of the icy plain's composition. Differing colors inside the "heart" suggest that it is made of a reservoir of ices, and some of these ices are moving away from the region. The ice isn't standard water ice, either — observations from the Ralph instrument, which sees in infrared, indicate that Sputnik Planum is made of nitrogen, carbon monoxide, and methane ices.

New Horizons is also getting more details about Pluto's atmosphere. After the spacecraft passed the dwarf planet, it looked back at the space rock with its Long Range Reconnaissance Imager (LORRI), capturing the Sun streaming through the gases surrounding Pluto.

These pictures indicate two distinct hazy layers — one 50 miles above the surface and another 30 miles up. However, the mists were seen as high as 80 miles above the surface. NASA thinks these hazes form when ultraviolet light from the Sun breaks up the methane gas particles already in the atmosphere. This breakdown causes other hydrocarbons in the atmosphere to fall lower and condense into ice particles — producing the haze.