Robert sent in a number of links. For example, https://www.livescience.com/space/nasa-solves-mystery-of-why-jupiters-io-is-so-volcanically-active … which immediately makes you wonder if the headline is too optimistic. According to new research by NASA scientists they have solved the secrets of the most volcanic body in our solar system. Io is a moon of Jupiter. It is estimated there are around 400 volcanoes active on Io – and it is just 3600 km in diameter. These eruptions, they say, can even be seen from Earth when viewed through large space telescopes. What is really going on?
The Juno spacecraft made two close flybys of Io in 2023 and 2024, approaching as close as 1500 km. It is described as having a bubbling surface. Hence the idea came about that a vast ocean of magma lies just under the surface of Io – in order to spout so much volcanic activity. Io orbits elliptically around Jupiter and therefore its distance from the large planet varies. It also means Jupiter’s gravitational pull must also vary as Io orbits. This means, it would seem, that Io is constantly under stress as a result of tidal flexing. The new research has put a bit of a spanner in the works as Io has been found to have a solid interior. Not one in which magma can well up from a magma lake just below the surface. The volcanoes must, therefore, be subject to individual magma chambers – which would be deep.
At https://www.livescience.com/space/planets/new-thunderstorms-wider-than-earth-are-spewing-out-green-lightning-on-jupiter-and-could-make-one-of-the-gas-giants-massive-bands-disappear … a pair of huge thunderstorms have been spotted swirling on Jupiter’s ‘south equatorial belt‘ and appear to be unleashing massive bolts of green lightning, they say. Jovian lightning is green, apparently, as a result of atmospheric ammonia.
Robert then supplies a link to https://www.holoscience.com/wp/closest-ever-picture-of-io/ … which goes back to 1999 – long before the Juno mission. This refers to an image produced by the Galileo spacecraft – in the late 1990s. The image of eruptions on Io gave rise to NASAs idea of a vast magma lake. One image targeted lava flows from volcano Pillen, volcanic features similar to those that ocurr on Mars and Earth. However, there are different types of lava flow on Io that have not been seen elsewhere – and in a small area. This led Thornhill, a proponent of electricity in space, to claim the clusters of pits and domes do not have a volcanic origin. Instead, he said, electric discharges between Jupiter and Io were happening, moving across the surface of Io. The movement, as if in a chain of volcanoes walking across the surface was more easily understood as a travelling arc. Galileo’s near infra red mapping spectrometer measured the temperatures of the lava flows during the eruption phase and found they were hotter than any known eruptions on Earth – over the last two billion years. It was the temperature of the cathode arcs that was being measured, he said. Better resolution will show Io’s hot spots are far too hot to be volcanic, a prediction that may yet turn out to be true. Thornhill is no longer with us so we cannot know how he would have responded to the Juno data.