Jupiter's Moons

Rohan Sakalkale and Stephen Grayson


Jupiter's four main moons, Europa, Callisto, Io, and Ganymede, are called the Galilean moons first discovered Galileo Galilei in January 1610. Besides being one of the most intriguing objects in the solar system, they are among the most massive objects in the solar system coming after the Sun and the other 8 planets of course Additionally, their radii surpasses that of even the largest dwarf planet giving a spectacular perspective of how large these moons really are.


The most interesting of all these moons is Europa due to the fact that it may be speculated to contain some presence of life forms due to a distinct similarity between the atmospheric conditions/compositions on Europa and the Earth. Additionally, it is very likely that if there were to be water hidden under the surface of the frozen martian planet, it could be encouraging the growth of microbial life. More over there is a significant amount of evidence that suggests plenty of oxygen exists which is vital for supporting life. The research is very significant due to the fact that it is estimated there may be more than a hundred times more oxygen than previously thought.

General Information:

  • Orbit of Europa around Jupiter (time) — 85 hours
  • Smooth Surface, no craters, active geologically
  • Temperatures on Europa — Average Minimum: -370 F; Average Temperature: -270 F; Average Maximum: -240 F
  • Smaller than Earth and moon, but larger than Pluto
  • Name comes from Queen of Crete (Greek Mythology); Abducted by Zeus


  • Very icy
  • Oxygen, Water, and Hydrogen = abundant
  • Ocean under surface
  • Ability to support life
  • Cracks from tidal force


The fifth moon that is closest to Jupiter is called Io. This moon has gained the reputation for having a robust amount of volcanic activity. Sulfur spews around 190 miles into the moons atmosphere while the whole surface of the moon is covered in volcanic lava. While it doesn't quite have the capacity to sustain life like Europa does, it is still none the less a very unique and interesting planet to learn about.

General Info:

  • Takes 1.77 Earth days to Orbit Jupiter
  • Min: -202 F; Max: 3000 F (Because of the Volcanoes)
  • Slightly larger than Moon
  • Name come from daughter of Inachus; terrible back-story to it
  • Several fly-bys: Pioneer 10 and 11; Voyager I and II


  • Inner core filled with Iron (gives reddish look)
  • Only one with distinct active volcanoes
  • atmosphere filled with sulfur dioxide (Jupiter's pull)
  • Water existed; taken away by Jupiter's radiation


Usually referred to as the dead moon of Jupiter, Callisto is the most heavily cratered object the solar system. Hardly any sort of geological activity happens on this celestial body; however if there is any activity it is generally caused by all of the rogue asteroids and comets that penetrate the moon.

General info:

  • 4.5 billion yrs old (Same as Jupiter)
  • Outer most moon
  • Same size as Mercury
  • Mean Temperature: -218.47
  • Orbit of Callisto around Jupiter (time) — 17 days
  • Name once again comes from Greek Mythology (one of the people Zeus seduces...)


  • Many craters
  • No geological change for 4 billion years (interesting)
  • Any changes have come from being hit by objects
  • Elements: Magnesium and iron-bearing hydrated silicates, carbon dioxide, sulfur dioxide, and possibly ammonia and other organic compounds.
  • Atmosphere: Very thin atmosphere; Carbon Dioxide and Molecular Oxygen


Referred to as the largest moon of Jupiter, Ganymede would be considered a planet if it weren't orbiting Jupiter. This massive beast also packs what is somewhat of an interesting story.

General Info:

  • 4.5 Billion yrs old
  • Larger than Mercury and Pluto (smaller than Mars)
  • Seven Earth days to Orbit
  • Min: -171; Max: -305 (unlikely for life)
  • Name: Trojan Prince
  • 3rd most outward moon


  • Core = Metallic Iron
  • Crust: icy rock
  • Two terrains: Dark Craters and lighter groves (possible flow of water in past)
  • Speculation of saltwater 124 miles under the surface
  • Atmosphere: Oxygen — too thin to support life; Magnetosphere interlinked with Jupiter's

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