The Rogues' Gallery

Jupiter's Moon Io: Two Weeks of Volcanic Hell

Bob Novella August 5, 2014 2 Comments

Jupiter’s moon-sized moon Io, had a hellacious couple of weeks last year as three extraordinary volcanoes put on an unprecedented display.

Io is the most volcanically active body in the solar system. More than any planet or moon known, even the earth. Earth isn’t even close actually. This inner-most Gallilean satelite is 25 times more active than our own planet with more than 400 active volcanoes. This has even earned it the moniker “pizza moon” due to its eruption-induced pock-marked countenance (hold the anchovies).

Why is this so? Wouldn’t such a small body have cooled solid after all this time? Perhaps, except for the tidal heating of course. Io’s close proximity to Jupiter and other large moons create gravitational gradients in its interior. The nearest part of Io is tugged harder than its farside. As the moon orbits and rotates, these areas that are tugged most and least move around as well causing a constantly moving kneading effect of the rock that heats it up. This heat is released like zits constantly erupting all over the place.

(FYI: Tidal heating was called into question in 2013.)

There’s usually some volcanic activity going on somewhere on Io therefore. Most is smallish or mediumish but every 1 or 2 years there’s a huge eruption that’s seen from earth. Last August though, astronomers spotted two heavy-weight eruptions going on. Just two weeks later there was a final salvo from a third volcano that was pretty much the biggest such event ever seen on the moon since its volcanic proclivities were discovered in the late 1970s.

These were truly remarkable events. They were actually hotter than any modern-day volcano on earth. I say modern-day because earth experienced much hotter eruptions early in its career than it does today. This was because the young earth experienced much more radiogenic heating then. This is caused by the heat energy released due to the decay of radioactive isotopes of uranium, thorium, and probably other shorter-lived ones.

What would you have seen on Io if you were there last year before you were brutally incinerated and turned to ash?

I’m glad you asked. You would have seen vast curtains of lava rising high into the sky spewing from miles long cracks in the crust of Io. You would have seen many cubic miles of lava spreading out over hundreds of square miles of the surface. Remember that eruption a few years ago on earth in Iceland from that volcano with the impossible name, Eyjafjallajokull? You’d be seeing eruptions ten thousand times bigger than that was. Almost worth being incinerated isn’t it?

I’m kinda annoyed we didn’t have a probe in orbit around Io when that happened, I wanna see hell in hi-resolution baby. Better yet, imagine if the moon experienced eruptions like that.

I’d never leave my backyard at night.

Press Release

Image Credit: Katherine de Kleer, UC Berkeley.