Nearly seven years after New Horizons visited Pluto, the little world is still revealing itself to be geologically complex.
On March 29, 2022, scientists announced that giant ice volcanoes created some of Pluto’s most unusual surface features.
Pluto’s giant ice volcanoes
When New Horizons flew past Pluto on July 14, 2015, it discovered a world unlike any we’d seen before. It saw mountains made of solid water ice (with caps of methane snow) and vast smooth glacier-like plains of nitrogen ice.
Now, in the latest research, scientists say that cryovolcanoes, or ice volcanoes, created some of Pluto’s most enigmatic terrain. These volcanoes spew “lava” composed of ice and water instead of molten rock.
Multiple large domes near Pluto’s ‘heart’
While studying images and other data sent back by New Horizons, the researchers found multiple large domes that appeared to be ice volcanoes.
The domes are located in a region known as Pluto’s “heart,” southwest of Sputnik Planitia. These are the nitrogen ice plains that roughly form the shape of a heart.
They range from about 1/2 to 4 miles (1 to 7 km) tall and 18 to 60 miles (30 to 100 km) across.
How did the giant ice volcanoes form?
The researchers ruled out ordinary erosion, due to significant variations in the highs and lows of the terrain
They also consider glacial erosion or sublimation erosion unlikely, because they’ve found no evidence for it in the hummocky terrain.
There is still a bit of a mystery, however. Pluto is so cold that even water containing ammonia or salts freezes quickly on its surface. So how did these water-ice flows occur?
The researchers say that Pluto may have retained more interior heat than previously thought. This heat could have persisted at least until the recent geological past.