1	Chapter 8 Jovian Planets Systems Chapter Outline The Jovian Worlds: A Different Kind of Planet Jovian Planet Interiors Jovian Planet Atmospheres Jovian Planet Magnetospheres A Wealth of Worlds: Satellites of Ice and Rock Jovian Planet Rings
2	Jovian Planets
3	Jupiter’s Interior Structure
4	Understanding Jovian Planet Sizes and Densities
5	Interior Structures of the Jovian Planets
6	Differential Rotation Solid body rotation - particles far from axis of rotation have same rotation period as ones near to axis Terrestrial planets Differential rotation - particles far from axis of rotation have different rotation periods from ones nearer to axis Jovian planets
7	Composition of Jovian Atmospheres
8	Cloud Patterns in Jovian Atmospheres
9	Jupiter’s Belts and Zones
10	Dynamics of Jupiter’s Atmosphere Three features Light-colored zones Dark-colored belts Light and dark ovals Observed streaming in atmosphere Complex interactions on boundaries between belts and zones Note waves on the boundaries between belts and zones
11	Jupiter’s Great Red Spot Great Red Spot has been observed since 1665 Thermally driven “storm” Vortexing motions Smaller ovals observed to move around spot Smaller ovals are also vortex motion
12	Jupiter’s Atmospheric Structure
13	Vertical Structure in Jupiter’s Atmosphere
14	Comet Shoemaker-Levy Impact with Jupiter
15	Galileo Probe, Dec. 7, 1995 Lightning common Wind speeds higher under cloud level, 650 km/h, than above Heat from interior drives winds On Earth solar radiation drives winds Probe found only traces of NH₃ and NH₄SH cloud layers and no H₂O clouds Higher heavy element content than Sun Less water than expected
16	Saturn’s Atmosphere Differential rotation as does Jupiter Atmosphere does have belts and zones Hazy above cloud layers make banded structure less distinct
17	Uranus’ Atmosphere From great distances appears as bland, featureless, blue-green planet Higher abundance of CH₄ than Jupiter and Saturn Does have clouds, but high altitude haze obscures NH₃ & H₂O frozen out, thus no NH₃, NH₄SH, or H₂0 clouds
18	Neptune’s Atmosphere Similar composition to Uranus Clouds more visible than Uranus
19	Jupiter’s Magnetosphere
20	Magnetic Fields – Conformation of Interior Structure Magnetic axis inclined to rotational axis Jupiter = 10^o, Saturn = 0^o, Uranus = 59^o, Neptune = 47^o, Earth = 10^o Jupiter, Saturn, Neptune magnetic axis oriented opposite that of Earth Magnetic center not geometric center for Uranus and Neptune
21	Why are the largest and the majority of the naturally occurring satellites associated with the Jovian planets? The availability of the icy planetesimals being more numerous in the vicinity of the Jovian planets should have lead to them having more satellites. The strong gravitational fields of the Jovian planets should have enhanced their ability to form and retain more and larger satellites.
22	Galilean Satellites of Jupiter
23	Jupiter’s Io Galileo spacecraft, 1997 Variety of surface colors probably result from sulfur and sulfur compounds ejected in numerous volcanic activity Pillan Patera plume on limb rises more than 190 km above Io’s surface Prometheus plume rises at least 100 km and casts a shadow
24	Jupiter’s Europa Numerous streaks and cracks are typically 20 to 40 km wide Upper inset shows details of dust covered surface Lower inset shows details of crater
25	Jupiter’s Ganymede Huge, dark, circular region called Galileo Regio, ancient remnant of ancient crust Lighter areas are younger than dark areas Bright shiny areas probably indicate presence of water ice
26	Jupiter’s Callisto Numerous craters pockmark icy surface Note series of circular rings on left marking region called Valhalla Numerous craters suggest surface is geologically inactive
27	Since Io is about the size of the Moon, should not it have have lost its primeval heat long ago as did the Moon? So why is the interior thought to be molten? Some radioactive materials may provide some heating of the interior by natural radioactive decay (fission). Primary heating source is likely to be gravitational/mechanical through frictional dissipation of mechanical energy.
28	Saturn’s Titan Thick opaque atmosphere of N₂, CH₄, and other hydrocarbons
29	Why would a ring system form about each of the Jovian planets and not another satellite? Availability of particles at the time of formation and strong gravitational fields of Jovian planets account for ring system. Close proximity of the particles to the planet must be part of the answer as to why the particles did not coalesce into another satellite.
30	Saturn’s Ring System 1995 rings almost edge-on to Earth Note thinnest of rings
31	Numerous Thin Ringlets in Saturn’s Ring System Ring particles vary in size from 1 cm to 5 m Most abundant are 10 cm size particles Constitutes small amount of matter (100 km satellite) Ring particles are dirty ice fragments from formation period (scattering) Dust particles fill Cassini and Encke divisions
32	Jupiter’s Ring System Rings closer to planet than satellites Composed of tiny rock fragments (not highly reflecting) Probably being continually replenished by material from Io Radiation pressure from Jupiter and Sun should move them away
33	Uranus’ Ring System
34	Neptune’s Ring System Thin, dark ring system similar to that of Uranus Two main rings Faint inner ring Particle sheet extends toward planet
35	The Big Picture Jovian planets may lack solid surfaces on which geology can work, but they are dynamic bodies with winds, huge storms, strong magnetic fields, and interiors in which materials behave in unfamiliar ways. Despite their relatively frigid temperatures, many Jovian satellites are geological active by virtue of their icy compositions. Ironically, it was cold temperatures in the solar nebula that led to icy compositions and hence geological activity. Ring systems owe their existence to small satellites formed about the Jovian planets billions of year ago. The rings are composed of particles liberated from those satellites surprisingly recently. Understanding the Jovian planets forced us to modify many of our earlier ideas, in particular by adding the concepts of ice geology, tidal heating, and orbital resonances.