Jovian Planets Rulers of the Solar System 5

Jovian Planets Rulers of the Solar System 5 A

Properties Mass (kg) Radius (km) Average Density (kg/m 3) # of Moons Mag. Rotation field Period (♁ =1 (days) ) Surface Temp. (K) Surface Gravity (♁ =1) Jupiter 1. 9 x 1027 71, 000 1330 16 14 0. 41 124 2. 5 Saturn 5. 7 x 1026 60, 000 710 18+ 0. 7 0. 43 97 1. 1 Uranus 8. 7 x 1025 26, 000 1240 21 0. 7 -0. 69 58 0. 91 Neptune 1. 0 x 1026 25, 000 1670 8 0. 4 0. 72 59 1. 1 • Most of Jupiter and Saturn and about half of Uranus and Neptune are made of Hydrogen and Helium 5 A

Voyager 5 A

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 A

Bands & Storms 5 A

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

Storms 5 A

The great red spot 5 A

SL 9 5 A

Interiors 5 A

Magnetosphere 5 A

Uranus’ orbit 5 A

Composition Size Jupiter Dust Small grains Saturn Water ice < house size Uranus Carbonaceous Large paricles Neptune dark, unknown, small 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 5 A

Rings 5 A

5 A

Ring structure 5 A

What makes the rings? 5 A

Shepard moons 5 A

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. 5 A