Lecture 18 & 19: Jovian planets, plus their moons and rings

Jupiter

-Largest planet in the solar system
-Mass is 317.8 times M*Earth
-Thick gaseous atmosphere surrounds a giant ball of liquid hydrogen
-Density increases towards the centre.
-Has very faint rings
-Many moons: 79 detected so far Jupiter

Juno Space Probe

Orbiting Jupiter right now!
Jupiter’s structure effects Juno’s orbit, allowing the interior to be probed

Jupiter’s Storms

-Jupiter’s atmosphere complex clouds and stable storms.
-Winds of up to 500km/hr.
-Bands and storms stable over decades.
-Wind bands are up to 3000 km thick!
-Reasons for the bands is not fully understood

Ammoni

Jupiter white clouds

Ammonium Hydrosulfide

Clouds are orange.

Saturn

-Second largest planet in the solar system.
-3.3 times less massive than Jupiter, but close to the same size
-Structure is much like Jupiter.
-Has spectacular rings.
-Many moons: 82 have names

Saturn’s Rings

The diameter of the rings is over 260,000 km, but they are less than 0.1km thick

Uranus

-Coldest planet.
-Small rocky core.
-Thick Water + Ammonia + Methane mantle.
-Thick H2/He atmosphere.
-Rotation axis tilted 98 degrees.
-Thin rings and lots of moons.

Neptune

-Furthest planet from the Sun.
-Structure very similar to Uranus
-Rotation axis tilted 28 degree.
-More surface features than Uranus.
-Strongest winds in the solar system: up to 2,100 km/h

Io: A moon of Jupiter

-The most geologically active object in the solar
system.
-Around the same size as the Earth’s moon.

Europa: A moon of Jupiter

-Surface covered with un- cratered Ice.
-Smaller than the Earth’s moon.
-There may be a huge ocean beneath the surface

Ganymede: A moon of Jupiter

-A little larger than the Earth’s moon.
-Surface includes some cratering, along with ancient geological activity

Callisto A moon of Jupiter

-A little smaller than Ganymede
-Surface is very heavily cratered.

Titan: Saturn’s moon

-Saturn largest moon

-Surfaces features hidden by
thick clouds.

-Titan has an atmosphere!

Iapetus: a moon of Saturn

-Very old cratered surface.
-Mostly made of Ices
-White is the natural colour (probably)
-Brown is a thin layer over the ice (maybe, but from where?)
-Giant ridge along the equator on the dark side.

There are craters along Iapetus’ mysterious ridge. What does this tell us?

The ridge formed billions of years ago

Enceladus: a moon of Saturn

-One of the most reflective objects in the solar system (very high albedo)
-Some parts are cratered and some are not.
-Active Methane Geysers!

Enceladus: a moon of Saturn

-Enceladus is relatively small...

-And yet is geologically
active.

Hyperion: a moon of Saturn

-Made mostly of water Ice
-Heavily cratered
-Dark material in the bottom of the craters

-Very porous –40% empty space

Miranda: a moon of Uranus

-Some craters.
-High ice content.
-Strange geological features

Triton: a moon of Neptune

-Temperature: -235C
-Surface is mainly frozen
nitrogen!
-Almost no atmosphere.
-Geologically active! (but water and ammonia, instead of lava)
-Orbits Neptune backwards.
-Probably a captured Dwarf Planet