True Giants of the Solar SystemJovian Planets

What’s Initially Available:

Solar Nebula - Composition

Beyond the “frost line”, ices can condense, allowing more massive planets to form

Refractories (rock, metal)

volatiles (ices & gas) and refractories

Why Planets & Not Stars?

• If mass > 0.08 solar masses, will be a true star, fusing H to He in core

• If 0.08 Msun > mass > 0.014 Msun (14 MJ) will, for a time, fuse deuterium (2H) into He and be brown dwarfs

• If mass is smaller, never achieve nuclear fusion in core - planets

Gas & Ice Giant Interiors

• Size versus Mass depends on composition - fight between gravity & pressure

• Differentiation causes the picture to be more complex

Interiors of Jovian Planets

Molecular H

Liquid Metallic H

IcesRock

Infrared Excesses

•J, S, N emit significantly more energy that they receive from the Sun!•Tail-end of formation/contraction process is still converting GPE into TE and leaking it into space.•Saturn requires an additional source, probably He raining out of LMH layer.•Uranus is a heat-wimp.

We will return to this later, when looking at their outer appearances - atmospheres.

Interior Conditions

from Guillot & Gautier 2015, Treatise on Geophysics, 2nd Ed.

Schematic representation of the interiors of Jupiter and Saturn. The range of temperatures is estimated using homogeneous models and including a possible radiative zone indicated by the hashed regions. Helium mass mixing ratios Y are indicated. The size of the central rock and ice cores of Jupiter and Saturn is very uncertain (see text). In the case of Saturn, the inhomogeneous region may extend down all the way to the core which would imply the formation of a helium core.

*HOWEVER

*Recent Result from Juno, which mapped out Jupiter's Interior

Its core is larger and more diffuse than originally thought

Collision?!

Newer Jupiter models:Debras & Chabrier2019, ApJ, 872, 100

Yes, solutions are not unique forUranus & Neptune, either.

from Guillot & Gautier 2015, Treatise on Geophysics, 2nd Ed.

Schematic representation of the interiors of Uranus and Neptune. The ensemble of possibilities for Neptune is larger. Two possible structures are shown.

Predicted cloud compositions: H2O deep, NH4SH medium, and NH3 high.

Outward appearances are determined by the run of temperature and pressure in their outer atmospheres

What We See

Jupiter

Saturn

Spots, Ovals, and other Features

Jupiter, the Great Red Spot (GRS), while ovals, aurora

GRS

Jupiter from Juno

https://youtu.be/NoQ0ClXrx8k

•Rotation & Coriolis Effect produce Cloud Bands

•Probably governed by fluid zonal flows extending deep into interiors

IR Emission Correlates with Depth

Cold

Cold

Cold

Warm

Warm

Cassini/Huygens 2004-2017

Color-enhanced views of Saturn

see http://www.spacescience.org/operations.php

Saturn from Cassini

Uranus - true color (left) and enhanced color (right)

Neptune

Mysterious Neptune

Winds can reach 1,100 mph!

Cloud Colors

• They shouldn’t have any!!• Jupiter & Saturn colors due to impurities - S,

organics, ??• Uranus & Neptune - mostly just CH4 gas

• October 2000 - “virgin” NH3 clouds unambiguously detected in wake of the Great Red Spot (fresh NH3 sucked up and condensed - hours later it is coated with contaminant)

Once-Every-Thirty-Years Storms on Saturn

Enceladus