Jupiter's Moons
Jupiter has at least 67 moons. But we can't possibly show ALL 67 of them! In this webpage, the 4 largest will be the focus: the Galilean Moons. They are Io (yes, just two vowels: I and O), Europa, Ganymede and Callisto.
Io Stats
Europa Stats
Ganymede Stats
Callisto Stats
Average Distance from Jupiter: 1 882 700 km
Mass: 1.46 times Moon Diameter: 4820.6 km Temperature: -139 C Rotation: 400.536 hours Revolution: 16.689 Earth days/1 Callisto rotation Namesake: Callisto was one of Artemis's (the hunter goddess) followers who attracted the attention of Zeus. As punishment for breaking her virgin vow, Callisto was turned into a bear and is now the Ursa Major (big bear) constellation. |
Jovian Moons Facts
- IO HAS VOLCANOES. These volcanoes spew sulfur, which is what gives the moon its colour. Io is the most geologically active object in the solar system. The tidal forces of Jupiter and the other Galilean moons causes the interior of Io to heat up, causing these volcanoes. Over 400 volcanoes exist on Io. All that sulfur has also made another moon. Amalthea (250 km long), red in colour.
- EUROPA HAS AN UNDERGROUND OCEAN. Underneath Europa's icy crust lies a layer of saltwater that could host extremophiles (bacteria that can withstand extreme conditions). These extremophiles will have to live through pitch darkness and lethal radiation from Jupiter. Ganymede also has a layer of saltwater beneath its crust. Europa also has one of the smoothest (if not the smoothest) surface in the solar system, despite the many cracks running along the surface.
- EUROPA HAS AN ATMOSPHERE. This very thin atmosphere is made of... oxygen! It's not the only moon with an atmosphere though.
- GANYMEDE HAS A MAGNETIC FIELD. This magnetic field is generated much the same way Earth's is: through the rotation of an iron core. Ganymede is also the largest moon in the solar system. Being larger than Mercury, it would certainly be a planet if it wasn't orbiting Jupiter.
- GANYMEDE'S SURFACE IS COLOURED ACCORDING TO AGE. Darker patches are older, while lighter patches are younger.
- CALLISTO IS MADE OF ROCK AND ICE. Half rock, half ice, this dead world is also the most heavily cratered object in the solar system. The ice on Callisto is water ice and dry ice (frozen carbon dioxide). It could also have a liquid ocean layer, but astronomers believe that chances of that are doubtful.