Chapter 9: Jovian Planets

The Galilean Moons (nearest to furthest)

Io, Europa, Ganymede, Callisto (IEGC)

Why do we believe “the Jovian system” formed almost like a mini solar system (orbits, densities, etc)

• the conditions in the outer solar nebula where Jupiter formed allowed for the accretion of large amounts of gas and ice, which led to the creation of a massive planet with a large variety of moons

• it was able to attract and capture material to form/capture its moons

• similar to how the planets in our solar system formed around the sun, the moons of Jupiter have their own unique orbits and densities depending on formation location

Io composition

all rock, no H2O

Io heat source

volcanic activity, tidal heating with Jupiter and Europa

Europa composition

rock with some ice, liquid H2O under thin ice coating

Europa heat source

moderate tidal heating

Ganymede composition

rock with some ice

Ganymede heat source

weak tidal heating, some radioactive heating

Callisto composition

rock/ice mixture, possible subsurface liquid H2O

Callisto heat source

possible radioactive heating

requirements of life Europa possesses

liquid water, chemical elements, moderate tidal heating

what might limit Europan life

radiation from Jupiter on surface, low temperatures, less oxygen, lack of volcanic, tectonic, and geological activity

Europa’s likely internal structure

iron and nickel core, rocky mantle, large liquid water ocean, ice shell

places where life could exist on Europa

subsurface saltwater ocean, below thick ice shell

why/how does Titan’s atmosphere exist?

• possible volcanic activity producing methane, release of gas trapped in interior

• NOT due to gravity (not big enough) nor saturn’s magnetic field

how does Titan’s atmosphere compare to Earth’s?

both atmospheres are primarily composed of nitrogen, but Titan’s atmosphere also contains methane (rather than oxygen, like Earth’s) and has a higher surface pressure and a lower temperature

What is the surface of Titan like?

possible liquid water, geysers, clouds and weather variations

What did Huygens find regarding Titan?

evidence of a liquid flow that had caused erosion, possibly methane, potential presence of lakes and seas, liquid hydrocarbon lakes at poles, Titan is warmed up enough that water creates pressure and is able to penetrate through the ice from below

Why do we believe Triton didn’t form around Neptune?

it orbits the planet in retrograde motion, opposite of neptune’s rotation, composition is different from other moons, with an icy surface and a rocky core

What is one of the likeliest locations for subsurface life and why?

around volcanic vents because they create chemical disequilibrium

How do volcanic vents create chemical disequilibrium and why is it important?

• create chemical disequilibrium by releasing hot, mineral-rich fluids that alter the chemical composition of the surrounding water

• is important because it provides the energy source for ecosystems in the absence of sunlight