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GEOL 3045: Planetary Geology. Lysa Chizmadia Saturn. Introduction. 2nd largest planet Sixth from Sun (or seventh) Eccentricity = 0.056 9.0 - 10.1 AU Axial Tilt = 25.3º Earth = 23.5º Orbital period = 29.5 years Rotational period = 10.2 hours (2nd fastest) Mass = 5.69 x 10 26 kg
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GEOL 3045: Planetary Geology Lysa Chizmadia Saturn
Introduction • 2nd largest planet • Sixth from Sun (or seventh) • Eccentricity = 0.056 • 9.0 - 10.1 AU • Axial Tilt = 25.3º • Earth = 23.5º • Orbital period = 29.5 years • Rotational period = 10.2 hours (2nd fastest) • Mass = 5.69 x 1026 kg • ~95 Earths • Volume = 8.27 x 1014 km3 • ~763 Earths • Average = 0.69 g/cm3 • = 5.52 g/cm3 (lowest density in solar system) • At least 63 moons Image from: http://www.nineplanets.org/saturn.html Image from: http://en.wikipedia.org/wiki/Saturn
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 Image from: http://solarviews.com/eng/saturn.htm
True color of N pole Atmosphere • Structure: • Upper clouds: NH3 crystals • Lower clouds: NH4SH and H2O • Winds among the highest in Solar System • < 500 m/s (~1800 km/h) • Northern hemisphere blue ~ Uranus • With trace amounts of: • NH3, C2H2, C2H6, PH3, CH4 Image from: http://www.solarviews.com/eng/saturn.htm Hexagonal Cloud Rotation in N pole Image from: http://en.wikipedia.org/wiki/Saturn
Clouds • Ices in clouds: • H2O, NH3, NH4SH • 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: http://www.nineplanets.org/saturn.html Image from: http://www.solarviews.com/eng/saturn.htm
Rings • Brightest of gas giants • Discovered in 1610 by Galileo • Structure: • <1 km thick Ring over Titan & Enceladus Spokes in Rings Rings edge-on Image from: http://www.nineplanets.org/saturn.html Image from: http://www.solarviews.com/eng/saturn.htm Images from: http://en.wikipedia.org/wiki/Saturn
Magnetosphere • ~ magnitude of Earth’s • 1/20th of Jupiter’s • Simple dipole • Extends slightly past orbit of Titan • 1.22 x 106 km • Probably produced by currents in liquid metallic H Saturnian auroral emissions Image from: http://www.solarviews.com/eng/saturn.htm
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 Thermal view of Saturn Thermal emissions Image from: http://en.wikipedia.org/wiki/Saturn Image from: http://www.solarviews.com/eng/saturn.htm
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