From processor Ted Styrk, “The Juno Jupiter orbiter flew by Io, Jupiter's super-volcanic moon, on May 16, returning arguably the best imagery of the moon since the Galileo Orbiter around the beginning of this century. Definitely the best since New Horizons in 2006.”
Image Courtesy of NASA/JPL-Caltech/SwRI
Kind of Cool Image of Io from Juno
The brightest spot is a radiation signature, but all the rest are thought to be active volcanos on the Io surface. The moons are not a primary target of the Juno mission, but they do occasionally take a peek to try and monitor such phenomenon at Io. Later when the mission is extended, Juno will explore the full Jupiter system with its rings and moons. Multiple rendezvous are planned for Ganymede, Europa, and Io.
Image is not visible light, but taken with an x-ray camera.