Analysis of images taken by New Horizon, a NASA probe, suggests Pluto's interior temperature has remained warmer than previously thought for long enough to allow for this phenomenon.

Instead of spouting lava, ice volcanoes discharge "a thick, wet mixture of water and ice, or maybe even a solid flow like that of glaciers", on Earth, Kelsi told AFP. Singer, a planetary scientist at the Southwest Research Institute in Colorado.

We know the existence of ice volcanoes on several moons of the solar system, such as Triton.

But those of Pluto "seem very different from anything we have seen so far," added this co-author of the study.

There are "large expanses of very large ice volcanoes, with a remarkable texture of undulating relief" on this star which is on the outskirts of the solar system.

Difficult to precisely date the formation of these volcanoes, "but we think that they can go back to a few hundred million years or even less", according to Ms Singer.

A straw in a story stretching back into billions of years.

Liquid water storage?

The region where these formations are devoid of impact craters, which are caused by asteroids, scientists do not exclude that ice volcanoes are still forming there.

These findings are "very important," Lynnae Quick, a planetary scientist specializing in cryovolcanism at NASA's Goddard Space Flight Center, told AFP.

"They suggest that a small celestial body like Pluto, which should have lost most of its internal heat a long time ago, managed to retain enough energy to fuel widespread geologic activity quite late in its history," he said. she elaborated.

"These insights should allow us to re-evaluate the possibility of liquid water conservation on small icy worlds far from the sun."

As on the moons of Jupiter, Ganymede, Europa and Callisto.

For his part, David Rothery, professor of planetary geoscience at The Open University in the United Kingdom, explained that "it is not known what provided the heat necessary for the eruption of these ice volcanoes".

One of these structures, Mount Wright, with some five kilometers high and 150 km wide, has a volume similar to one of the Earth's largest volcanoes, Mauna Loa in Hawaii.

And this while Pluto is considerably smaller than the Earth.

So much so that the star, the ninth in size in the solar system, was reduced in 2006 to the rank of dwarf planet.

The New Horizon probe, which took the images, was the first spacecraft to explore Pluto in 2015, which has Kelsi Singer marveling that "we still have so much to learn about the solar system".

© 2022 AFP