Hotspot volcanoes

The explosive story of “space volcanoes” on 9 worlds close to “fire and ice”


First it was Fagradalsfjall in Iceland. Now Cumbre Vieja is erupting in La Palma in the Canary Islands.

2021 has been an explosive year on our planet so far, but it’s not the only place in the solar system where volcanoes have made the news.

This week, moon rocks returned to Earth when China’s Chang’e-5 mission revealed that the Moon was volcanically active a billion years more recently than previously thought. Scientists last month found evidence that Arabia Terra in northern Mars has experienced thousands of “super eruptions” over a period of 500 million years that could have changed the climate of the Red Planet. .

Neither the Moon nor Mars are no longer geologically active, but there are many places where one can find “space volcanoes” … although they are not quite what you might expect.

“Our view of volcanoes is very skewed from what they look like on Earth – a conical-shaped mountain, often with a snow-capped peak that shatters some sort of hot molten rock,” said Natalie Starkey, geologist and cosmochemist and author of “Fire and ice: the volcanoes of the solar system, ”Which posted last week. “It was only through NASA’s Voyager missions that we discovered that there are volcanic worlds elsewhere, but these volcanoes do not look like those on Earth.” Starkey’s excellent book is the first to examine these extraterrestrial volcanoes in our solar system.

It is an explosive reading in more than one way.

“Some are similar to Earth’s volcanoes in the inner solar system, such as the volcanoes of Venus and the 15-mile / 25-kilometer-high Olympus Mons on Mars, which looks a lot like Mauna Kea in Hawaii,” Starkey said. . “When we get to icy moons, we find volcanic behavior, but not necessarily conical shaped mountains. ”

Volcanoes are part of a planetary body’s efforts to cool itself, releasing excess heat into space. For geologists, it’s instant proof that a world is active. “The same thing happens even on frozen worlds – they’re always hotter inside than outside and that heat wants to move,” Starkey said. “So it only takes a slight change in temperature to turn frozen water, methane or ammonia into a liquid.” So on a frozen world, it’s liquid water / ammonia / methane rather than liquid rock that spurts out of a hot core.

Yes, space volcanoes are pretty weird, and they’re getting even more so.

Here’s where you’ll find them in the Solar System, and they’re not where you think they are:

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Venus: second planet from the Sun

Venus is the new Mars, with five missions to visit over the next decade. But should he be on this list? “We have no valid evidence that it is still erupting today,” Starkey said. “But there is a lot of evidence to suggest that it has active volcanoes on its surface.”

What’s odd about Venus is that its surface is the same age – around 500 million years old – largely because it lacks plate tectonics like we have on Earth. “It has the same amount of heat to lose as Earth because it’s roughly the same size so it builds up, and then there’s a huge event where all that heat is released over a few hundred million dollars. ‘years,’ Starkey said.

There are probably around 37 volcanoes that could still be active and may have recently erupted from lava and gases, but the atmosphere is difficult to see through, hence the multitude of impending exploration missions, such as DAVINCI + , which will include a lander.

Io: moon of Jupiter

The most volcanically active world in the solar system, Io is the most interior Galilean moon of Jupiter and is believed to harbor an underground ocean of magma. “It has a constant heat source due to the warming tides of Jupiter,” Starkey said. Io is in a constant gravitational tug-of-war with Jupiter and the other large moons, so much so that it changes shape during its 42-hour orbit.

It is this constant friction and energy that makes Io so hot – and therefore so volcanic – to such an extent that an ocean of magma exists below its surface. Io exhibits eruptions that are orders of magnitude larger than what’s happening on Earth today. “It should continue to be so volcanic as long as it is next to Jupiter and the other Galilean moons.”

Europe: moon of Jupiter

Europa, the fourth largest of Jupiter’s 79 moons, has fractures on its icy surface that make it look like a “venous eyeball”. It is an indication of its volcanism. “Europe is almost certainly volcanically active,” Starkey said. “The easiest way to find out is by its surface – if it’s covered in craters, that indicates it hasn’t been remade.” There are a few craters visible over Europe, but not many. “It’s geologically interesting because it must have been active recently,” she said.

Enceladus: moon of Saturn

“Enceladus has a hot rock core, just like Earth, but there is a huge ocean of salt water covered in ice,” Starkey said. This ice cap is, in fact, its crust, through which salt water gushes out of the ocean in the form of geysers, but not like those found on Earth, which are linked to volcanic activity, but are not produced by a volcano.

“On Enceladus, these geysers or plumes are literally the magma of this body coming out from within,” Starkey said.

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Titan: moon of Saturn

Saturn’s largest moon has rain and flash floods, lakes and oceans, atmosphere, and humidity. There is ice composed not of water, but of liquid ethane and methane. Titan is the most similar place in the solar system to Earth despite its very different chemistry. But the volcanoes?

“There are definitely volcanoes, which probably release methane, and there could also be an underground ocean where heat meets salt water,” Starkey said. Microbes? It’s possible. “This is exactly how we think life started on Earth,” Starkey said. “Titan is definitely an active world, and that’s what we’re looking for. ”

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Miranda and Titania: the moons of Uranus

The smallest and innermost of Uranus and the eighth largest moon in the solar system, respectively, are sort of a volcanic conundrum. Miranda was overtaken by NASA’s Voyager 2 spacecraft in 1986. “These two worlds look like evil worlds from a sci-fi movie, but they are very interesting geologically,” Starkey said. “We don’t know much about these frozen worlds and we have to go back.”

Miranda (which has a 12 mile deep canyon) is half ice and half rock, with terraced layers that indicate the coexistence of older and newer surfaces. One theory is that partially melted ice is forced upward to create new surfaces. Titania also has canyons and there is evidence of tectonic activity and ice volcanoes.

It is estimated that Miranda, Titania, and three other moons of Uranus – Ariel, Umbriel, and Oberon – could have, or did have, liquid water under their icy surfaces.

Triton: moon of Neptune

“Triton was the first world outside the solar system that we found to be cryo-volcanically active,” Starkey said. Most of what we know about Triton comes from a flyby performed in 1089 by Voyager 2, the spacecraft’s final target in its mission. “We’ve seen streaks and plumes on the surface that look like little lit fires – some kind of plume or volcanic activity, but we have a lot of questions about Triton,” Starkey said. “It’s probably a captured moon and it’s probably being pulled and pushed by Neptune.” Cue warming tides like the one found on Io in Jupiter… but with an ocean too.

Triton was identified as the highest priority ocean world candidate in the January article “NASA’s roadmap to ocean worlds”.

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Pluto: dwarf planet in the Kuiper belt

Triton is known as Pluto’s twin, so it’s no surprise that everyone’s favorite ex-planet may also be home to cryo-volcanic activity. How do we know? The New Horizons flyby in 2015 showed us a smooth surface with no craters and no ammonia detected, which lowers the temperature at which ice water melts and creates a mud, sort of lava.

He also discovered what could be an ice volcano called Wright Mons, which could be the largest volcano discovered in the Outer Solar System. It shelters only one impact crater.

I wish you clear skies and big eyes.