Jupiter’s Satellites

Jupiter currently has the largest known number of satellites in the solar system, with 67 known moons (as of August 2014). The four largest moons were discovered by Galileo Galilei and are called the Galilean Satellites or moons. They are Callisto, Europa, Ganymede, and Io, with Io having the closest orbit to Jupiter. And Ganymede is larger than planet Mercury.

Jupiter’s Galilean Satellites

Brief Descriptions

Callisto

  • A heavily-cratered iceball

Europa

  • Liquid water oceans below the “crust”

Ganymede

  • Biggest in the solar system, tectonic twists

Io

  • Most active volcanoes in the solar system, Sulfur
Image Jupiter’s Galilean satellite Callisto with heavily-cratered iceballs.
Callisto via NASA Galileo SpacecraftPublic Domain | Image courtesy of NASA.
Image Jupiter’s Galilean Satellite Europa with possible liquid water oceans below the crust.
Europa via NASA Galileo SpacecraftPublic Domain | Image courtesy of NASA.
Image Jupiter’s Galilean Satellite Ganymede, the biggest in the solar system with tectonic twists.
Ganymede via NASA Galileo SpacecraftPublic Domain | Image courtesy of NASA.
Image of Jupiter’s Galilean satellite Io.
IoPublic Domain | Image courtesy of NASA.