1. 5A Jovian Planets Rulers of the Solar System

2. 5A Properties Most of Jupiter and Saturn and about half of Uranus and Neptune are made of Hydrogen and Helium Mass (kg) Radius (km) Average Density (kg/m 3 ) # of Moons Mag. field ( ♁ =1) Rotation Period (days) Surface Temp. (K) Surface Gravity ( ♁ =1) Jupiter1.9 x 10 27 71,000133016140.411242.5 Saturn5.7 x 10 26 60,00071018+0.70.43971.1 Uranus8.7 x 10 25 26,0001240210.7-0.69580.91 Neptune1.0 x 10 26 25,000167080.40.72591.1

3. 5A Voyager

4. 5A Energy With no surface, no surface modification processes –No craters –No volcanoes –No tectonics –No erosion These are big planets Big planets have lots of internal energy With no endogenic surface processes, where does the energy go?

5. 5A Bands & Storms

6. 5A Bands Differential rotation – poles take longer to rotate than equator

7. 5A Storms

8. 5A The great red spot

9. 5A SL9

10. 5A Interiors

11. 5A Magnetosphere

12. 5A Uranus’ orbit

13. 5A Planetary Rings All the “Jovian planets” have rings These are not solid, but composed of millions of tiny particles of ice and dust Rings have structure: gaps and spokes CompositionSize JupiterDustSmall grains SaturnWater ice< house size UranusCarbonaceousLarge paricles Neptunedark, unknownunknown, small

14. 5A Rings

15. 5A

16. 5A Ring structure

17. 5A What makes the rings?

18. 5A Shepard moons

19. 5A Planetary rings – Why? Left to itself, a ring will slowly spread out due to gravitational interactions Rings are bounded by the stronger gravity of larger bodies: The planet itself and some of the larger and nearby moons Some bounds are due to gravitational resonances, others due to the direct action of sheparding satellites The origin of the rings is unknown – either a failed satellite or a broken satellite A reason is known: the tidal stability limit at 2.5 times the radius of the body. Interior to this, 2 touching particles will be pulled apart by the planet’s gravity Why don’t inner planets have rings? Gravitation perturbations by the Sun will cause any small particles to spiral into the planets on a relatively short time scale.