Rain Is Impossible on Pluto. Its Glacier Looks Wet Anyway.

Thin dark streaks run across the frozen heart of Pluto, threaded between ice cells the size of cities. Researchers say they look wet. The likeliest liquid is nitrogen, and it appears to be coming up from below.

The heart is Sputnik Planitia, a nitrogen glacier bigger than Oklahoma and Texas combined. NASA's New Horizons images from 2015 and 2016 show its northern edge. A team led by Alan Stern of the Southwest Research Institute reexamined those images and argues the dark markings appear to get briefly wet now and then, probably from liquid nitrogen seeping up through cracks.

Rain is off the table; Pluto's air and cold rule it out. So the researchers compared the streaks with Landsat 9 views of Earth sites such as Greenland's ice sheet, where narrow dark bands mark places that liquid water has reached. The two look strikingly alike.

Models led by Orkan Umurhan of the SETI Institute offer a mechanism. They show frozen nitrogen at the glacier's base can melt. Driven up by pressure or buoyancy, the liquid could climb through slender channels resembling lava tubes, then stay fluid for a while, trickling downhill and darkening the ice.

Earlier work pointed to ancient liquids on Pluto. The Planetary Science Journal published this study in August. It suggests liquid nitrogen lies beneath the glacier or did not long ago. The glacier's surface is probably under 1 million years old.

How solid nitrogen melts under strain at such temperatures has never been studied closely in a lab, Umurhan says. The process might also help explain the geysers Voyager 2 spotted on Triton, a moon of Neptune.

The wet streaks turn up in only one place. More than half of Pluto has never been photographed closely enough to say whether that place is special.

Read the full story at Southwest Research Institute, August 5, 2026

Hot Take: Pluto appears to have rising damp. Any English homeowner knows what comes next. A very expensive survey.