Io’s Underground Magma Ocean

By | December 12, 2019

Earth’s moon might look like it’s made of cheese, but Jupiter’s moon Io seems a lot more delicious. I mean, look at this thing. It’s like a giant pizza with all kinds of crazy toppings. Io has all those blobs for a good reason. It’s full of active volcanoes. So many that it’s the most volcanically active body in the solar system. We’re talking more than 150 active volcanoes — some with 400 kilometer high eruptions. But those weird looking spots are also a kind of mystery because the volcanoes on Io aren’t where astronomers expected to find them which might mean that the moon has an underground magma ocean. The mystery comes from how Io’s volcanoes are thought to form which has to do with the gravitational pull of Jupiter and two other moons: Europa and Ganymede. As Io orbits Jupiter, the gravity from each of these worlds tugs its insides in a particular way. It’s called Tidal Flexing and it stretches the moon, deforming its surface by up to 100 meters at a time. Io’s insides are getting stretched and squeezed and the friction from all that rock moving around produces a lot of heat. Like, enough heat to melt the rock into magma in some spots. So, for a long time, astronomers have been using what we know about the way Jupiter and its moons orbit to predict exactly where the hot spots should be. And you would think that Io’s volcanoes would be right on top of those hot spots. It would make sense for the magma to be erupting from the places that have the most of it, but it turns out that’s not where the volcanoes are. In 2013, a group of researchers led by an astronomer named Christopher Hamilton, modelled Io’s tidal flexing to map out the warmer spots. When they compared that map to the actual locations of the moon’s volcanoes they found that the volcanoes were shifted much farther east by 30 to 60 degrees. They came with two main reasons why that could be. The first possibility is that we’re wrong about how fast Io rotates. If it spins faster, then its insides might be heating up more and messing with the volcanic plumbing. The hot spots could be in totally different places — shifted east, for example. Or, the model for Io might have been off because of the magma ocean astronomers think is hiding below Io’s surface. Scientists have found evidence for an ocean like this before. Back in 2011, a separate team of researchers predicted that Io had a magma ocean 30 to 50 kilometres beneath the crust which would help explain some unexpected measurements the Galileo probe detected in Jupiter’s magnetic field In a paper published in the Astrophysical Journal Supplement Series in June, 2015 a third group, which included Hamilton, modelled how an underground magma ocean like that would affect the flow of heat inside Io. The ocean in their model would cover the entire moon and it would be kind of sponge-like, slowly moving around below the surface, thanks to the tidal pull caused by Jupiter, Ganymede and Europa. The researchers found that this flowing magma could explain the shift in the volcanoes’ locations by generating even more friction and heat as it moves. Which means that the mystery of Io’s misplaced volcanoes might just be another piece of supporting evidence for the idea that there is a hidden layer of magma ocean sloshing around inside the moon. Thanks for watching this episode of SciShow Space and thanks especially to our patrons on Patreon who make this show possible If you wanna help us keep making episodes like this and also get access to some stuff that you can’t get access to any other way you can go to to learn more and don’t forget to go to and subscribe.

100 thoughts on “Io’s Underground Magma Ocean

  1. KambEight Post author

    So Jupiter has a moon with a water ocean and a moon with a magma ocean? Someone alert Robert Frost.

  2. TomRaj Post author

    It may be the most volcanically active body in the solarsystem, but it wont have the largest eruptions til I move there πŸ˜‰

  3. Carrie Wright Post author

    Love you Hank, you're so cute. Plus, I love hearing about moons.

  4. Gilgamesh Post author

    If gravity of Jupiter creates heat on the moon, could not humans create endless amounts of energy with that volcanic heat?

  5. Peter Schmidt Post author

    Out of curiosity, why does Callisto have no effect on Io, but the other big moons do?

  6. PinkChucky15 Post author

    Sometimes I love learning about the moons more than the planets πŸ™‚

  7. Round Mango Post author

    Thought the thumbnail was the Jabulani football, from the 2010 Fifa World Cup.

  8. Nena Vaskina Post author

    Our solar system is so cool, a planet that's like a freaking greenhouse oven 24/7 and earth (which is obviously a cool planet) and a moon with an atmosphere and methane lakes and clouds and ice, moons with under-surface oceans of water and magma, planet with pretty patterns, planet with pretty rings, planet with 3000km/h winds… And there's exoplanets made of diamond and shit like damn there's trillions of different planets and moons I wonder what other cool stuff there is

  9. Alyssa S Post author

    "it looks like a giant pizza'"
    no it looks like a rotten egg

  10. Andrew Wells Post author

    What is a magma ocean? How is it different than what we have?

  11. Marcus Hall Post author

    My brother saw the first picture of IO and said "that looks like a good soup".

  12. renaissanceexodus Post author

    How is a "magma ocean" different from our own molten core? Is it just a matter of the entire mantle being molten as well as the core?

  13. Zanzibar Haberdasher Post author

    The city of York has a street named Whip-ma-whop-ma-gate.
    Your welcome.

  14. Physics Videos by Eugene Khutoryansky Post author

    It took me a few seconds to realize that this was not a picture of cheese, but an actual picture of the moon IO.

  15. DocWolph Post author

    So would being on Io's surface feel like a constant earthquake…. moonquake… intense seismic event?

  16. Thinker Post author

    A layer of magma beneath the crust, isn't that just mantle?

  17. Nicholas Coffin Post author

    Aren't giant underground magma oceans kind of a common thing? Like, aren't we on a thin little crust floating on top of a giant underground magma ocean right now?

    I get how Io is small enough that you wouldn't expect to find one there if it weren't for the unusual circumstances surrounding that moon, but I'm pretty sure a giant underground magma ocean is still just a mantle anyway…

  18. Frankgel CarreyΓ³ Post author

    So much information in such a short time… Thank you for explaining things this way!

  19. alexanderx33 Post author

    So does Io have horizontal movement of tectonic plates, or is it all vertical? Are the hot spots just piling mass on top of the crust pushing the bottom of the crust further down which then melts?

  20. The Fnish Post author

    A giant pizza or a mouldy, disgusting looking planet
    But seriously, what is with these moons and their fucking oceans!

  21. Insert name here Post author

    IO does look like cheese, just cheese that has been left out way too long.

  22. Stefan Oosterhout Post author

    Could you at some point explain how the gravity of Jupiter heats up the moon? I understand the concept, but it seems to violate the law of conservation of energy. This heat-energy must come from somewhere. If it's gravity, does that mean that the potential energy between the moon and Jupiter decreases (which would over time lead to a smaller orbit until the moon falls into Jupiter)?

  23. Entrippy Post author

    has anyone had any issues with youtube playing 2 videos at once? im trying to pay attention, but naruto and sauske are fighting in the background…

  24. Myrkskog Post author

    Or they could be eruptions of electrically charged particles similar to those seen on most comets, in particular on 67P.

  25. ParadoxBassCube Post author

    0:08 SciShow I like your videos, but io doesn't look like a "Pizza". I mean common. it's obviously a blue-red spaghetti square with rainbow lazered banana cats all over its face.

  26. Brandon Hall Post author

    Europa, Enceladus, Ganymede, CalistoΒ and now Io? What is it with all these moons having subsurface oceans of some kind?

  27. Karl Frederik Færch Fischer Post author

    How is geographical directions determined on other planets? Hank said that the volcanoes were shifted further east, but what is 'east' on other planets? Is it by rotation, and if so does it change anything if the planet/moon is found to have a magnetic core? what if it rotates in funny ways or is tidally locked?

  28. Jorus Linnenbank Post author

    Could it be, that with the constant gravitational pull on Io, the volcanos errupt at the 30/60 degree angle because the planet is being stretched into an oval shape by Jupiter, Europa and Ganymede?
    It only seems logical that the volcanoes errupt in these angles because that's the part of the surface which is being stretched (due to structural weaknesses in the crust formed because of these gravitational pulls)

  29. ConoriHam Post author

    What's the difference between a magma ocean and a mantle? Seems like those are the same to me

  30. TheGameDoplhin Post author

    I never understood the movie 2001: A Space Odyssey

  31. Kevin D Post author

    Sometimes I am amazed at how much we know about about stars unimaginably distant, but don't know the rotation speed of an object in our own solar system. Unless the speed isn't constant due to all that shape-changing and such, why would we not know Io's rotation speed?

  32. Mickey Lev Post author

    Is there a video about "Planet Nine" in the works?
    Dying to know what that's all about

  33. cefarix Post author

    Well, it looks like your next episode's got to be about Planetnine!

  34. Ethan McDonald Post author

    Where does all the kinetic energy come from? If the orbit and tidal forces Jupiter has on the moon can heat up it's insides, where does the kinetic energy come from?

  35. Ryan Lowry Post author

    You guys MUST do a video on the (possible) 9th planet!

  36. Yoshu GonzΓ‘lez Post author

    SciShow Space What is the speed of Gravity???

    Make a video about that

  37. Tony Gordon Post author

    What exactly is the difference between a magma ocean and a mantle? They seem like two labels for the same thing to me.

  38. Adam Horne Post author

    I really like the video of that volcano erupting what a sight! its very amazing how a moon is capable of such volcanic activity! thanks for the vid sci show!

  39. metroid 6464 Post author

    there is a background noise in his videos what is it?

  40. coc0s Post author

    It must be nice to be patronized by patronage of Patreon patrons.


    No mention of Callisto?


  42. Broockle Post author

    Do Tidal forces contradict conservation of energy?
    Europa and Io seem to receive a ton of energy from their orbit around Jupiter. Are they losing energy in another department anywhere? Is their orbit becoming smaller as a result or something? That would reduce their gravitational potentual.
    Because otherwise you could create a perpetuum-mobile with Tidal forces xD

  43. Benjamino Post author

    I hope Hank realises he will be a hologram in the distant future teaching cyborg children about their field trips

  44. Adam Thornton Post author

    It was only a few years ago I learned Earth's mantle wasn't a gigantic underground magma ocean.

  45. Laurynas Zubavičius Post author

    SO we know who is a teenager in our solar system

  46. ForeverOfTheStars Post author

    If Io has a magma ocean Europa has to have a water ocean.

  47. chveniani Post author

    I have a question – from where comes that energy to heat up entire planet exactly? I mean okay gravity moves rocks around and it causes a heat generation, but gravity is a force, it's not a energy source right? In the closed system from where would that energy come from? Somehow it has to be transformed from other type of energy due to energy conservation, am I right?

    Thanks for great videos and so much of content creation! You guys are fantastic! keep it up

  48. Galactic Scholar Post author

    Love the videos! Keep up the amazing work!

  49. Janice R R Tolkien Post author

    Slow down there buddy. Can't understand you after my cranberry vodka.

  50. g0ldbuG Post author

    How is an underground magma ocean different from a genuine mantle besides its thickness?

  51. FieryWingedAngel Post author

    Wait, how does tidal stretching produce heat? Where is that energy coming from?

  52. shoblidoo bfjfie Post author

    wow look, they actually dumbed down so much they did actually turn dumb, remarkable πŸ™‚

  53. Searching For Myself Post author

    I can imagine life thriving in Io's magma oceans and looking at Earth or even Europa and discounting the possibility of life there. (Too cold, no energy sources, toxic water)

  54. Vennom Scandi Post author

    looks more like a rancid pizza actually.

  55. Riko J. Amado Post author

    Dang it, Hank. With the way I've noticed you inflect certain words I am disappointed that you missed the opportunity to pronounce "magggg-ma" with quotation fingers!

  56. Joe C Post author

    Hey science show, what about terra forming Jupiter's moon Ganymede. It's bigger than the planet mercury and has an oxygen nitrogen atmosphere.


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