Jupiter and Its Moons Photograph courtesy NASA This family portrait, a composite of the Jovian system, includes the edge of Jupiter (with the Great Red Spot visible) and Jupiter's four largest moons, known as the Galilean satellites. From top to bottom are Io, Europa, Ganymede, and Callisto. The smallest of these four moons, Europa is about the size of Earth's moon.
JUPITER’S MOONS — CLOSE-UP These four views show the great surface variety present on Jupiter’s large satellites. We see volcanic deposits on Io, ice fractures on Europa, grooved terrain on Ganymede, and impact basins on Callisto. The relative ages of these surfaces range from Io, the youngest, through Europa and Ganymede, to Callisto, the oldest. Prepared for NASA by Stephen Paul Meszaros
Jupiter, Europa & Callisto [Pin It] Credit: NASA/JPL/University of Arizona NASA's Cassini spacecraft captured this image on Dec. 7, 2000, just as two of Jupiter's four major moons, Europa and Callisto, were nearly perfectly aligned with each other and the center of the planet.