How Hot Is Io's Magma?

July 16, 2023
David Sunnyside

A volcano's lava can be as hot as 2,200 degrees Fahrenheit. That's almost three times hotter than the hottest sunlit surface of Mercury, the planet closest to the sun.

Io's volcanic activity isn't caused by the shifting of tectonic plates like on Earth, but by a different process called tidal heating. In tidal heating, the gravity of a large object (in this case Jupiter) squishes and stretches another nearby object (Io's rocky lithosphere) to a point where it becomes flexible enough to warm up with friction.

This process can also form molten layers below the lithosphere, and scientists believe that this is where Io's volcanic activity comes from. But they've been puzzled by why night temperatures near Io's poles are about the same as those near its equator, even though Io gets more direct sunlight at the equator.

One possibility is that a magma ocean lies underneath the lithosphere. This ocean could be fed by a layer of hot, silicate mantle that rises through the molten layer. But scientists can't yet determine the exact temperature of the magma ocean, so it's not clear whether this explains Io's unusual heat balance.

More data from the new ALMA observations will help scientists figure out how hot Io's magma is. This will help scientists make better predictions of how volcanic eruptions on Io occur, such as when and where they might happen. Scientists have also noticed that the volcanic gases emitted by Io's volcanoes are more likely to contain potassium chloride than sodium chlorine, which is consistent with magma chamber temperatures that fall within the range at which these two chemicals can form.

David Sunnyside
Co-founder of Urban Splatter • Digital Marketer • Engineer • Meditator
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