In Depth | Io – NASA Solar System Exploration
Jupiter's rocky moon Io is the most volcanically active world in the solar system, with hundreds of volcanoes, some erupting lava fountains dozens of miles (or kilometers) high.
In Depth | Ganymede – NASA Solar System Exploration
Jupiter’s moon Ganymede is proving to be a fascinating world. Not only is it the largest moon in our solar system, bigger than the planet Mercury and the dwarf planet Pluto, but NASA’s …
In Depth | Amalthea – NASA Solar System Exploration
Orbiting within Io's orbit, which is the innermost of the four largest moons of Jupiter (called the Galilean moons), are four smaller moons named Metis, Adrastea, Amalthea, and Thebe.
In Depth | Europa – NASA Solar System Exploration
Jupiter’s moons Io, Europa, and Ganymede are in what is called a resonance – every time Ganymede orbits Jupiter once, Europa orbits twice, and Io orbits four times.
In Depth | Callisto – NASA Solar System Exploration
Callisto was discovered Jan. 7, 1610, by Italian scientist Galileo Galilei along with Jupiter’s three other largest moons: Ganymede, Europa and Io. Callisto is named for a woman turned into a …
Callisto - NASA Solar System Exploration
Jun 26, 2019 · Italian astronomer Galileo Galilei discovered Callisto and Jupiter’s other three large moons: Ganymede, Io and Europa. The discovery led to the understanding that planets in our …
Volcanoes and Auroras Glow in Eclipse Movie of Jupiter's Moon Io
Feb 4, 2001 · shows bright spots of hot lava and changes in auroral glows. These images from NASA's Cassini spacecraft provide evidence that the auroras originate in electrical currents …
Jupiter - NASA Solar System Exploration
Sep 3, 2025 · Before NASA’s Juno mission, three of Jupiter’s four largest moons, known as Galilean moons — Io, Europa, and Ganymede — were shown to produce these distinct …
Galleries | Callisto – NASA Solar System Exploration
Oct 21, 2025 · This composite image includes Jupiter with its Great Red Spot. and from top to bottom: Io, Europa, Ganymede, and Callisto.
Io By the Numbers - NASA Solar System Exploration
May 16, 2024 · The speed needed for an object to break away from the gravitational pull of a planet or moon.