A Surprising Discovery in a Frozen Land
Scientists analysing data from NASA's New Horizons mission, which flew past Pluto in 2015, have found compelling evidence of something long thought impossible on such a cold world. They believe that liquid nitrogen may be seeping up from deep below the
surface of a vast glacier, a process that could still be happening today. This finding, published in the Planetary Science Journal, is the first to suggest recent liquid activity on Pluto. It fundamentally alters our view of the dwarf planet, transforming it from a static ball of ice and rock into a potentially dynamic world with ongoing geological processes.
Clues in Pluto's Icy Heart
The evidence comes from a massive, heart-shaped glacier of frozen nitrogen on Pluto's surface called Sputnik Planitia. It's an enormous feature, larger than the states of Texas and Oklahoma combined. Images from New Horizons revealed strange, dark patterns and streaks along the boundaries of city-sized convection cells on the glacier's northern edge. Researchers noticed these features looked a lot like areas on Earth's own ice sheets where meltwater has darkened the snow and ice. Since it's far too cold for liquid water on Pluto's surface, scientists began to suspect another liquid was at play: nitrogen.
How Liquid Nitrogen Could Exist
While rain on Pluto is physically impossible due to its thin atmosphere and extreme cold, the new study proposes a different mechanism. Computer models suggest that heat radiating from Pluto's rocky core could be just enough to melt the nitrogen ice at the very bottom of the kilometers-deep Sputnik Planitia glacier. This creates reservoirs of liquid nitrogen. Because liquid nitrogen is less dense than the solid ice above it, this liquid would be buoyant. Scientists believe it could be forced upward through cracks and conduits in the ice, similar to how magma travels through volcanic tubes on Earth. Once it reaches the surface, it could flow for a short time before refreezing, darkening the ice and creating the features New Horizons observed.
A New Chapter for Pluto
This discovery forces a major rethink of the dwarf planet. The idea that Pluto still retains enough internal heat to melt nitrogen suggests it is far from a geologically dead world. This internal warmth might come from the slow decay of radioactive elements within its core, a process that has been happening for billions of years. While this liquid nitrogen ocean is not the kind of water-based ocean that could host life as we know it, its existence is profound. It shows that even in the frigid, dark depths of the outer solar system, worlds can be surprisingly active. According to Alan Stern, the principal investigator for the New Horizons mission, “Pluto never stops surprising us.”
