Generations of amateur astronomers have enjoyed watching the shadows of Jupiter’s Galilean moons periodically sweep across the giant planet’s cloud tops as they pass in front of the Sun. These “shadow transits” are clearly visible reminders of the clockwork nature of the solar system, easily enjoyed with even modest telescopes. But from its perch in polar orbit around Jupiter, NASA’s Juno spacecraft provides a bird’s eye view of the huge planet’s cloud tops that is unmatched by even the largest telescopes on Earth. In June, the spacecraft’s Junocam instrument captured spectacular views of Io’s shadow as the volcanic moon moved into eclipse, producing a jet black, sharply defined “spot” atop the turbulent atmosphere. Junocam is a public outreach camera, providing data to citizen scientists who then process the pictures seen here. Launched in August 2011, Juno is designed to study Jupiter’s internal structure, gravity and magnetic/radiation environment. The spacecraft braked into orbit around Jupiter in July 2016.
