NASA Scientists Reveal 44-Year-Old Mystery of How and Why Jupiter’s IO Is So Volcanically Active NASA scientists with the Juno mission to Jupiter figured out a solution to a 44-year-old mystery of the subsurface beginnings of the planet’s moon which had very active geologic features.

As the innermost of Jupiter’s Galilean moons, Io offers a glimpse into some of the most extreme geologic phenomena in the solar system. Roughly the size of Earth’s Moon, Io’s surface is marked by intense volcanic activity,