Saturn Astronomy 311 Professor Lee Carkner Lecture 18

Which of the following is a major component of Jupiter’s clouds? a)Water b)Ammonia c)Molecular hydrogen d)a and b only e)a, b, and c

In what region does Jupiter generate its strong magnetic field? a)Rock/ice core b)Liquid metallic hydrogen mantle c)Molecular hydrogen atmosphere d)Dust ring e)Alternating cloud bands

Saturn -- King of the Titans   He was overthrown by Jupiter who became king of the gods  Saturn’s symbol is the sickle

Viewing Saturn from Earth   First viewed through a telescope by Galileo   Modern telescopes reveal a series of rings and cloud patterns in Saturn’s atmosphere

Saturn Facts  Size: 9.5 Earth diameters   Orbit: 9.5 AU   Description: smaller, more distant Jupiter with rings

Viewing Saturn from Space   Hubble Space Telescope has provided many images   Orbiting Saturn to study it long term  Dropped a probe (Huygens) into Titan’s atmosphere

Path of Cassini

Saturn’s Atmosphere  Saturn has belts, zones, ovals and storms, but they are less distinct than on Jupiter    Colors tend to be yellow, white and brown  Saturn sometimes has storms that burst up from below

Composition of Atmosphere   Top layer of Ammonia (NH 3 )  Middle layer of Ammonium Hydrosulfide (NH 4 SH)   We don’t see all of the layers as clearly as we do on Jupiter

Saturn’s Dullness  The temperature of Saturn’s atmosphere increases more slowly with depth than Jupiter because:   Due to weaker gravity the layers are more spread out  As a result    Upper layers obscure the deeper layers

Saturn and Jupiter’s Atmospheric Structure

Saturn’s Heat   Saturn is smaller than Jupiter and should have radiated much of its heat away by now   Theory: the helium condensed into droplets and fell towards the core liberating gravitational energy   Calculations seem to support this

Saturn’s Interior   Saturn is also the most oblate planet   The density is low due to a much smaller liquid metallic hydrogen mantle   Saturn has a magnetosphere but it is not as strong as Jupiter’s  Due to slower rotation, less liquid hydrogen and blocking of charged particles by the rings

Internal Structure of Jupiter and Saturn

HST Views the Rings Edge-On

Rings and Tides   This is the region where the tidal force pulling the material apart is stronger than the gravitational force holding it together

Structure of the Rings   Rings are separated by gaps or divisions with relatively few particles   The size and composition of particles vary from ring to ring   F ring has many small, dark particles

Diagram of Saturn’s Rings

Moons and the Rings  Several moons have orbits within the rings   Moons may also be a source of ring material  Examples of moons effecting the rings:   The Encke gap has a small moon, Pan, in it 

Next Time  Read Chapter

Summary  Saturn is the second largest planet and the second closest gas giant to Earth  Saturn is similar to Jupiter with key exceptions mostly due to less mass and smaller gravity  cloud layers are more spread out in depth  less distinct cloud bands  larger core  less liquid metallic hydrogen

Summary: Rings  Made up of many distinct rings and ringlets  Composed mostly of icy particles of various sizes and reflectivity  Ring structure shaped by moons  Rings cannot form a larger body due to tidal forces