WASHINGTON, March 29 (Reuters) – A batch of domed ice volcanoes unlike anything else known in our solar system and which may still be active have been identified on Pluto using spacecraft data NASA’s New Horizons spacecraft, showing that this distant frigid world is more dynamic than previously known.

Scientists said Tuesday that these cryovolcanoes – possibly 10 or more in number – are between six-tenths of a mile (1 km) and 4-1/2 miles (7 km) high. Unlike Earth’s volcanoes, which spew molten gas and rock, cryovolcanoes on this dwarf planet extrude large amounts of ice—apparently frozen water rather than other frozen material—that can have the consistency of a toothpaste, they said.

Features on the asteroid belt dwarf planet Ceres, Saturn’s moons Enceladus and Titan, Jupiter’s moon Europa, and Neptune’s moon Triton have also been considered cryovolcanoes. But these all differ from Pluto, the researchers said, due to different surface conditions such as temperature and atmospheric pressure, as well as different mixtures of icy materials.

“The discovery of these features indicates that Pluto is more active, or geologically alive, than we previously thought,” said planetary scientist Kelsi Singer of the Southwest Research Institute in Boulder, Colorado, lead author of the study published in the review. Nature Communication.

“The combination of these geologically recent features, covering a large area and most likely consisting of water ice is surprising because it requires more internal heat than we thought Pluto would have at this point in its history,” Singer added. .

Pluto, which is smaller than Earth’s moon and has a diameter of about 1,400 miles (2,380 km), orbits about 3.6 billion miles (5.8 billion km) from the sun, or about 40 times farther than Earth’s orbit. Its surface presents plains, mountains, craters and valleys.

The images and data analyzed in the new study, obtained in 2015 by New Horizons, validated previous hypotheses about cryovolcanism on Pluto.

The study not only found plenty of evidence for cryovolcanism, but also that it lasted a long time, not a single episode, said Alan Stern, planetary scientist at the Southwest Research Institute, New Horizons principal investigator and co-author of the ‘study.

“What’s most fascinating about Pluto is that it’s so complex — as complex as Earth or Mars despite its small size and great distance from the sun,” Stern said. “This was a real surprise from the New Horizons flyby, and the new cryovolcanism finding underscores that again in a dramatic way.”

The researchers analyzed an area southwest of Sputnik Planitia, Pluto’s large heart-shaped basin filled with nitrogen ice. They found large domes 18 to 60 miles (30 to 100 km) in diameter, sometimes combining to form more complex shaped structures.

An elevation called Wright Mons, one of the tallest, may have formed from the fusion of several volcanic domes, resulting in a shape unlike any volcano on Earth. Although different in shape, it is similar in size to the great Mauna Loa volcano in Hawaii.

Like Earth and the other planets in our solar system, Pluto formed about 4.5 billion years ago. Based on an absence of impact craters that would normally accumulate over time, it appears that its cryovolcanoes are relatively recent – ​​formed over the past hundreds of millions of years.

“It’s young on a geologic timescale. Because there are almost no impact craters, it’s possible these processes are ongoing even today,” Singer said.

Pluto has a lot of active geology, including flowing nitrogen ice glaciers and a cycle in which nitrogen ice vaporizes during the day and condenses into ice at night – a process that constantly alters the planetary surface.

“Pluto is a geological wonderland,” Singer said. “Many areas of Pluto are completely different from each other. If you only had a few pieces of a Pluto puzzle, you would have no idea what the other areas look like.