GEOL 3045: Planetary Geology Lysa Chizmadia Saturn Lysa Chizmadia Saturn

Introduction  2nd largest planet –Sixth from Sun (or seventh)  Eccentricity = – AU  Axial Tilt = 25.3º –Earth = 23.5º  Orbital period = 29.5 years  Rotational period = 10.2 hours (2nd fastest)  Mass = 5.69 x kg –~95 Earths  Volume = 8.27 x km 3 –~763 Earths  Average  = 0.69 g/cm 3 –   = 5.52 g/cm 3 (lowest density in solar system)  At least 63 moons  2nd largest planet –Sixth from Sun (or seventh)  Eccentricity = – AU  Axial Tilt = 25.3º –Earth = 23.5º  Orbital period = 29.5 years  Rotational period = 10.2 hours (2nd fastest)  Mass = 5.69 x kg –~95 Earths  Volume = 8.27 x km 3 –~763 Earths  Average  = 0.69 g/cm 3 –   = 5.52 g/cm 3 (lowest density in solar system)  At least 63 moons Image from: Image from:

Internal Structure  Atmosphere (59.5 km): –~93% H & ~7% He  Depleted in He relative to solar  Molecular Hydrogen upper mantle –>100,000 bars –Earth atmosphere ~1 bar  Metallic Hydrogen lower mantle –>1,000,000 bars –Liquid H lower mantle  H nuclei do not have lattice order  Rocky-Ice Core: –9-22 x Earth  Atmosphere (59.5 km): –~93% H & ~7% He  Depleted in He relative to solar  Molecular Hydrogen upper mantle –>100,000 bars –Earth atmosphere ~1 bar  Metallic Hydrogen lower mantle –>1,000,000 bars –Liquid H lower mantle  H nuclei do not have lattice order  Rocky-Ice Core: –9-22 x Earth Image from:

Atmosphere  Structure: –Upper clouds: NH 3 crystals –Lower clouds: NH 4 SH and H 2 O  Winds among the highest in Solar System –< 500 m/s (~1800 km/h)  Northern hemisphere blue ~ Uranus  With trace amounts of:  NH 3, C 2 H 2, C 2 H 6, PH 3, CH 4  Structure: –Upper clouds: NH 3 crystals –Lower clouds: NH 4 SH and H 2 O  Winds among the highest in Solar System –< 500 m/s (~1800 km/h)  Northern hemisphere blue ~ Uranus  With trace amounts of:  NH 3, C 2 H 2, C 2 H 6, PH 3, CH 4 Image from: Hexagonal Cloud Rotation in N pole Image from: True color of N pole

Clouds  Ices in clouds: –H 2 O, NH 3, NH 4 SH  Similar to Jupiter –Average cloud T: - 185ºC  Colder than Jupiter  Bands due to circulation zones –Tropical zones –Wider than Jupiter  Winds up to 500 m/s  Great White Spot: –Occurs once every Saturnian year  ~ every 30 y –Next one in 2020  Ices in clouds: –H 2 O, NH 3, NH 4 SH  Similar to Jupiter –Average cloud T: - 185ºC  Colder than Jupiter  Bands due to circulation zones –Tropical zones –Wider than Jupiter  Winds up to 500 m/s  Great White Spot: –Occurs once every Saturnian year  ~ every 30 y –Next one in 2020 Image from: Image from:

Rings  Brightest of gas giants  Discovered in 1610 by Galileo  Structure: –<1 km thick  Brightest of gas giants  Discovered in 1610 by Galileo  Structure: –<1 km thick Images from: Spokes in Rings Ring over Titan & Enceladus Image from: Rings edge-on Image from:

Magnetosphere  ~ magnitude of Earth’s –1/20th of Jupiter’s  Simple dipole  Extends slightly past orbit of Titan –1.22 x 10 6 km  Probably produced by currents in liquid metallic H  ~ magnitude of Earth’s –1/20th of Jupiter’s  Simple dipole  Extends slightly past orbit of Titan –1.22 x 10 6 km  Probably produced by currents in liquid metallic H Saturnian auroral emissions Image from:

Heat Output  Radiates more Q than receives from Sun –Due to contraction (shrinks ~2 cm/yr) –He raining out of the atmosphere  N hemisphere twice as hot as S hemisphere  Radiates more Q than receives from Sun –Due to contraction (shrinks ~2 cm/yr) –He raining out of the atmosphere  N hemisphere twice as hot as S hemisphere Image from: Thermal view of Saturn Image from: Thermal emissions

Summary  2nd largest planet in solar system –Very fast rotation (day)  Atmosphere has fastest winds in solar system  Interior P & T high –Liquid metallic H mantle  Rings have high albedo = icy dust  Radiates more heat than receives from Sun –Due to contraction & He rain –N hemisphere hotter than S hemisphere  2nd largest planet in solar system –Very fast rotation (day)  Atmosphere has fastest winds in solar system  Interior P & T high –Liquid metallic H mantle  Rings have high albedo = icy dust  Radiates more heat than receives from Sun –Due to contraction & He rain –N hemisphere hotter than S hemisphere