Moons of Jupiter to Know for Intro to Astronomy

Jupiter's moons are fascinating worlds that showcase a variety of geological features and potential for life. From the volcanic activity on Io to the icy ocean of Europa, these moons offer insights into the complexities of our solar system.

1. Io

   • Most geologically active body in the solar system, with over 400 active volcanoes.
   • Surface is covered with sulfur and sulfur dioxide frost, giving it a colorful appearance.
   • Strong tidal heating caused by gravitational interactions with Jupiter and other Galilean moons.
   • Has a thin atmosphere primarily composed of sulfur dioxide.

2. Europa

   • Believed to have a subsurface ocean beneath its icy crust, making it a candidate for extraterrestrial life.
   • Surface features include ridges and cracks, indicating tectonic activity.
   • The ice shell is estimated to be 10-30 kilometers thick, with the ocean potentially being 100 kilometers deep.
   • Has a very thin atmosphere, primarily composed of oxygen.

3. Ganymede

   • Largest moon in the solar system, even bigger than the planet Mercury.
   • Unique for having its own magnetic field, likely generated by a liquid iron or iron-sulfide core.
   • Surface features include a mix of two types of terrain: bright, icy regions and darker, heavily cratered areas.
   • May also have a subsurface ocean, similar to Europa.

4. Callisto

   • Most heavily cratered object in the solar system, indicating a very old surface.
   • Lacks significant geological activity, suggesting a stable and ancient history.
   • May have a subsurface ocean, but evidence is less certain compared to Europa and Ganymede.
   • Has a thin atmosphere composed mainly of carbon dioxide.

5. Amalthea

   • Smallest of the four Galilean moons, irregularly shaped and heavily cratered.
   • Composed mainly of porous, low-density material, suggesting a primitive composition.
   • Acts as a source of dust for Jupiter's rings, particularly the Gossamer Ring.
   • Its low gravity allows for a very thin atmosphere, primarily composed of hydrogen.

6. Himalia

   • Largest irregular moon of Jupiter, likely captured by its gravity.
   • Has a dark surface, indicating a composition rich in carbonaceous materials.
   • Exhibits a non-spherical shape due to its low gravity and irregular orbit.
   • May have a very thin atmosphere, but details are not well understood.

7. Thebe

   • Small, irregularly shaped moon with a heavily cratered surface.
   • Orbits close to Jupiter, contributing to the dynamics of the planet's ring system.
   • Its low density suggests a composition of ice and rock.
   • Has a very weak gravitational field, making it difficult to retain an atmosphere.

8. Metis

   • Smallest of Jupiter's inner moons, with a highly irregular shape.
   • Closest moon to Jupiter, with a rapid orbital period of about 7.1 hours.
   • Heavily cratered surface indicates a lack of geological activity.
   • Contributes to the dust in Jupiter's ring system, particularly the Main Ring.