Exploring Jovian Planets: Deep Dive into Interiors, Moons, Atmospheres, and Features, Slides of Earth, Atmospheric, and Planetary Sciences

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Jovian Planet Systems

(Chapter 11)

Based on Chapter 11

• This material will be useful forunderstanding Chapters 12 and 13 on“Remnants of ice and rock” and“Extrasolar planets”• Chapters 3, 4, 5, 6, 7, 8, 9, and 10 on“Why does the Earth go around theSun?”, “Momentum, energy, and matter”,“Light”, “Telescopes”, “Our planetarysystem”, “Planetary geology”, and“Planetary atmospheres” will be useful forunderstanding this chapter.

Goals for Learning

• What are the interiors of jovian planetslike?• What is the weather like on jovian planets?• What are the moons of jovian planets like?• How where those moons formed?• Why do jovian planets have rings?

Jupiter and Saturn are mostly H, He with few percent ofices/rock/metalUranus and Neptune are mostly H

O, CH 2

, NH 4

(compounds of 3

hydrogen, ices) with some hydrogen/helium and few percentof rock/metalsWhy are J/S different from U/N?

Jupiter: 318 M

, 1.33 g/cmEarth

3

Saturn: 95 M

, 0.71 g/cmEarth

3

Jupiter is 3x heavier than Saturn. Why isn’t it 3x larger?Same chemical compositions, why are the densities so different?

Adding a pillow increases the height,but not by the full width of one pillowPillows are compressible (squishy)

Jupiter: 318 MEarth, 1.33 g/cm

3

Saturn: 95 MEarth, 0.71 g/cm

3

Jupiter is heavier than SaturnJupiter is more dense than SaturnHydrogen and helium arecompressibleIf you add more and morehydrogen to Jupiter, it will keepgetting heavierWill its density keep increasing?Will its radius keep increasing?

If you add a little moremass to Jupiter, then itsradius will still increaseIf you add a lot more massto Jupiter, its radius willactually get smallerReason:How materials, such ashydrogen, respond tochanges in pressure atVERY high pressures

Gravity pulls material inwardsRotation flings material outwardsnear the equator

Rapid rotation andrelatively weakgravity makeSaturn 10% widerat equator than polesThis equatorial bulgekeeps moons andrings in the equatorialplaneThe shapes of rockyterrestrial planetslike Earth and Marsare also affected bythis process –despite havingsurfaces of solid rock

70000 km radius10x Earth

Layered structure, liketerrestrial planetsChemical composition doesn’tchange much with depth untilthe coreLayers are changes of phaseGas -> Liquid -> “Metallic”Metallic hydrogen is a fluid,not really a solid. Liquid is atsuch high pressure thatelectrons can move freely.It conducts electricity easily.Magnetic field generated here.Core = 10 Earth masses, butsame size as EarthVery high densityJupiter is not a giant gasbag

All mixed together, not separatedinto rocks and metals and ices

Other Interiors

• Saturn = same as Jupiter• Uranus = same as Neptune• U/N:

Hydrogen gasWater/methane/ammonia mantleRock/metal core

• Is mantle liquid or solid?

Jupiter’s atmosphericstructure

Jupiter has three cloud layersHighest altitude/lowest temperaturecloud is ammonia (NH

) 3

Intermediate cloud is a compoundof ammonia and waterLowest altitude/highest temperaturecloud is water (H

O) 2

Other, less common, chemicalsare responsible for the coloursSimilar clouds on Saturn, Uranus,and NeptunePlus methane (CH

) on Uranus and 4

Neptune only – why?

Neptune

Global Winds on Jupiter

• One convection cell per hemisphere on anon-rotating planet, three per hemisphereon Earth, many on Jupiter – why?• This leads to alternating bands of risingand falling air• On Earth, rising air at equator makes lotsof clouds and rain forests, falling air at 30Nmakes few clouds and deserts• What do you expect to happen on Jupiter?

Brown middle cloud layer covers the whole planetWhite top layer of ammonia clouds only form in rising airAmmonia snow falls out of clouds, as air moves north or south, then descendsDescending ammonia-poor air doesn’t have enough ammonia to form clouds

Visible

Infra-red

Brown middle cloud layer is warmer than white, high altitude ammonia cloud layerCompare visible and infra-red imagesVery fast winds, hundreds of miles per hour all the time

Visible

Infra-red

Great Red SpotAn old, big storm

Textbooks say “Jupiter has onlyone Great Red Spot”

Weather on other jovian planets• What causes bands on Jupiter? Should wesee them on the other jovian planets?• Which of the jovian planets have seasons?What information do you need to answer?

Jupiter, Saturn, Uranus, and Neptune all havedramatic weather patternsJupiter, Saturn, and Neptune all have bandingSaturn and Neptune don’t show seasonal changes,despite 20

o^ axial tilt – internal heat? Large storm, Great Dark Spot, seen on Neptune, butvanished 6 years laterUranus had no storms/banding 20 years ago, but doesnow. Strong seasons likely due to large axial tilt andlack of any internal heat.

MOONS

Lots of moons, lots of diversitySmall: <300 km diameter,no geological activityMedium: 300-1500 km diameter,past geological activityLarge: >1500 km diameter,present geological activityMade of 50% ice, 50% rock,unlike objects in the innersolar system

Orbits and Rotation

-^ Most medium and large moons– Circular orbits in planet’s equatorial plane– Orbit in same direction as planet’s rotation– So formed by accretion in mini-nebula around planet, not

captured later– Rotate once per orbit, like Earth’s moon, due to tidalforces from planet

-^ Small moons– Irregular orbits, not always circular, not always in

equatorial plane, not always in expected direction– Mostly captured objects

Five smaller moons ofSaturnMoons with diametersless than ~300-400 kmare not sphericalTheir gravitational forcesare not strong enoughto deform their rigid iceand make it flow “downhill”

Where do the names come from?Each planet has a theme for the names of its moons.Jupiter: Lovers of Jupiter and related Greek/Roman mythological namesSaturn: Titans, giants conquered by Jupiter in Roman mythologyUranus: Characters from ShakespeareNeptune: Greek/Roman mythological characters related to the sea

The four Galilean satellites of Jupiter. Unresolved points of light until 1980.Io: Volcanoes, very activeEuropa: Ice crust above a liquid water ocean, active surfaceGanymede: Some old regions, some young regions, also an internal oceanCallisto: Heavily cratered iceballComposition trendIo: Mostly rock, some iceCallisto: Mostly ice, some rock

Io: Only othervolcanically activeworld in the solarsystem Lava is accompanied by sulphur and sulphur dioxide gasCondensed sulphur = red, orange.Condensed sulphur dioxide = whiteAll this gas gives Io a thin atmosphere