The study authors figured that ... it—a mechanism they described as “tidal heating.” They conjectured that Io may be the most intensely heated rocky body in the solar system. “One might speculate that widespread and recurrent surface volcanism would occur,” they ...
The study authors figured that Jupiter’s gravity must therefore be constantly kneading Io, pulling its surface up and down by up to 100 meters, and, per their calculations, generating a lot of frictional heat within it—a mechanism they described as “tidal heating.” They conjectured that Io may be the most intensely heated rocky body in the solar system. “One might speculate that widespread and recurrent surface volcanism would occur,” they wrote.The magma wants to escape; the water really doesn’t.” Liquid rock is less dense than solid rock, so it wants to rise and erupt quickly; the new study suggests that it doesn’t linger at depth long enough inside Io to form a massive, interconnected ocean. But liquid water is, unusually, denser than its solid icy form. “Liquid water is heavy, so it collects into an ocean,” Sori said. “I think that’s the big-picture message from this paper,” Sori added. Tidal heating might struggle to create magma oceans.Nimmo and coauthors offered one idea in a paper published in Nature in December: Maybe Earth’s moon was like Io. The moon was significantly closer to Earth back then, and the gravitational fields from the Earth and the sun were battling for control. At a certain threshold, when the gravitational influence of both were roughly equal, the moon might have temporarily adopted an elliptical orbit and gotten tidally heated by Earth’s gravitational kneading.Its interior might have remelted, causing a surprise secondary flourish of volcanism. But exactly where within the moon’s interior its tidal heating was concentrated—and thus, where all that melting was happening—isn’t clear. Perhaps if Io can be understood, so too can our moon—as well as several of the other satellites in our solar system with hidden tidal engines.