07 Outer Planets

1. Summary of Jovian Planets

Basics of Jovians



Fast Rotation

Magnetic Fields

Moons of Jovians

Ring System

2. Jupiter (#5)

Jupiter’s Convection

The colored bands in Jupiter’s atmosphere are associated with vertical convective motion.

As on Earth, surface winds tend to blow from high- to low-pressure regions.

Jupiter’s rapid rotation channels those winds into an east–west flow pattern, as indicated by the three yellow-red arrows drawn atop the belts and zones.

Zonal Flow

The wind speed in Jupiter’s atmosphere, measured relative to the planet’s internal rotation rate. Alternations in wind direction are associated with the atmospheric band structure.

Jupiter's Rotation Period: ~ 10 hours


Great Red Spot

Bottom Left: The cyclic motion of the Great Red Spot, imaged by the Cassini spacecraft. Right Panel: Closeup detail of the Great Red Spot taken by NASA's Juno on 11 July 2017.

Red Spot Junior (a) Between 1997 and 2000, astronomers watched as three white ovals in Jupiter’s southern hemisphere merged to form a single large storm. Each oval is about half the size of Earth.

(b) In early 2006 the white oval turned red, producing a second red spot! The color change may indicate that the storm is intensifying. 

Brown Oval A break in upper cloud layer (northern hemisphere). Deeper atmosphere looks brown. The oval’s length is approximately equal to Earth’s diameter.

Internal Structure

Jupiter's Magnetosphere

Ring System

Galileon Moons

Io. Its surface is kept smooth and brightly colored by the moon’s constant volcanism. Orange color is probably from sulfur compounds in the ejecta.

Io is very close to Jupiter and also experiences gravitational forces from Europa. The tidal forces are huge and provide the energy for the volcanoes.

The plume measures about 150 km high and 300 km across.

Europa. (a) It has no craters; surface is water ice, possibly with liquid water below.

Tidal forces stress and crack ice; water flows, keeping surface relatively flat.

(b) Europa’s icy surface is only lightly cratered, indicating that some ongoing process must be obliterating impact craters soon after they form. The origin of the cracks crisscrossing the surface is uncertain.

(c) This picture shows a smooth yet tangled surface resembling the huge ice floes that cover Earth’s polar regions. This region is called Conamara Chaos.

(d) This picture shows "pulled apart" terrain that suggests liquid water upwelling from the interior and freezing, filling in the gaps between separating surface ice sheets.


It is the largest moon in the solar system; larger than Pluto and Mercury

Its history similar to Earth’s Moon, but it contains water ice instead of lunar rock.

(a) and (b) The dark regions are the oldest parts of the moon’s surface and probably represent its original icy crust.

The lighter, younger regions are the result of flooding and freezing that occurred within a billion years or so of Ganymede’s formation. The light-colored spots are recent impact craters.

(c) Grooved terrain on Ganymede may have been caused by a process similar to plate tectonics on Earth.

The image suggests erosion of some sort, possibly even caused by water 


(a) It is similar to Ganymede in overall composition, but is more heavily cratered.

The large series of concentric ridges visible at left is known as Valhalla. Extending nearly 1500 km from the basin center, the ridges formed when "ripples" from a large meteoritic impact froze before they could disperse completely.

(b) This picture displays more clearly its heavy cratering. 

3. Saturn (#6)


Saturn’s Zonal Flow Winds on Saturn reach speeds even greater than those on Jupiter. As on Jupiter, the visible bands appear to be associated with variations in wind speed.

Saturn Storms (a) Circulating and evolving cloud systems on Saturn, imaged at approximately 2-hour intervals. (b) This infrared image, displayed in false color:

Dragon Storm It generated bursts of radio waves resembling the static created by lightning on Earth.

Polar Vortex It is at south pole. It has a well-developed eye wall and calm winds at its center.

The size of this vortex is slightly larger than the entire Earth, and its winds are about twice that of a category 5 hurricane on Earth 


Ring System

Spokes in the Rings Saturn’s B ring showed a series of dark temporary “spokes”. The spokes are caused by small particles suspended just above the ring plane.

Shepherd Moon (a) Saturn’s narrow F ring appears to contain kinks and braids. Its thinness can be explained by the effects of two shepherd satellites that orbit near the ring—one a few hundred kilometers inside, the other a similar distance outside.

(b) One of the potato-shaped shepherd satellites (Prometheus here roughly 100 km across) can be seen at the right of this enlarged view. 

F Ring Structure Kinks, waves, and other substructure in the F ring can be seen. A back-and-forth dance of the shepherd moons gravitationally sculpts clumps in the core of the rings.



The structure of Titan’s atmosphere. The solid blue line represents temperature at different altitudes. The inset shows the haze layers in Titan’s upper atmosphere, depicted in false-color green 

Titan Revealed

Titan’s Interior It appears to be largely a rocky-silicate mix.

The subsurface layer of liquid water, similar to that hypothesized on Jupiter’s Europa and Ganymede.

4. Uranus (#7)


Seasons on Uranus

5. Neptune (#8)

In the closer view, resolved to about 10 km, shows cloud streaks ranging in width from 50 km to 200 km.

Neptune’s Dark Spot. Similar in structure to Jupiter’s Great Red Spot. The entire dark spot is roughly the size of planet Earth. 

The cloud features (mostly methane ice crystals) are tinted pink because they were imaged in the infrared, but they are really white in visible light. Note that the Great Dark Spot has disappeared in recent years. 

Moons of Uranus and Neptune

Miranda (Uranus)

It has a strange, fractured surface suggestive of a violent past, but the cause of the grooves and cracks is currently unknown 

Triton (Neptune)