This global view of Jupiter’s moon, Io, was obtained during the tenth orbit of Jupiter by NASA’s Galileo spacecraft. Io, which is slightly larger than Earth’s Moon, is the most volcanically active body in the solar system.
Io Transit of Jupiter The three snapshots of the volcanic moon rounding Jupiter were taken over a 1.8-hour time span. Io is roughly the size of Earth's moon but 2,000 times farther away. J.Spencer(Lowell Observatory)& NASA/ESA