Saturn from HST Saturn from Voyager a 9

Saturn from HST

Saturn from Voyager a 9. 5 AU P 29. 5 yr i (orb) 2. 5 o e 0. 056 Prot 0. 43 d i (rot) 27 o R 9. 5 RE M 95 ME r 0. 69 g/cc g 1 g. E vesc 36 km/s A 0. 46

Oblateness of Saturn

Saturn Highlights • • Magnetic field about 2/3 of Earth’s Atmosphere and interior structure similar to Jupiter Yellowish-tan clouds and fewer dynamic storms Rings are splendoriforous!

Saturn’s Magnetosphere

Multi-Wavelength Saturn

Saturnian Atmosphere

Interior of Saturn

Internal Heat of Saturn • Sat. receives on 25% as much sunlight as Jup. • Yet, Sat. emits 50% more than what it absorbs! • Similar to Jup. , but for same reason? Ø No! Heat from gravitational contraction should now be gone, since Sat. is smaller • Instead, He may be draining thru metallic H mantle to the core, thereby liberating heat • In hotter Jup. , He remains dissolved – no draining Ø Consequence: He depleted in Sat. atm. – explains why He/H = 1/4 for Jup. but 1/7 for Sat.

Artsy “Ring World” • 1610: Galileo first observed the rings of Saturn, but not clearly; appeared more like appendages (sorta like a triple planet) • 1660’s: Rings clearly seen to encircle the planet; ring gaps discovered (Cassini’s division, Encke’s division) • 1859: Maxwell shows that the rings cannot be solid • 1895: Keeler confirms Maxwell with measurements

The Rings of Saturn • • Rings are 200, 000 km across, but less than 0. 2 km thick! Consist mostly of icy particles, ranging in size from 1 cm to 10 m Rings reside inside the Roche Limit Main features: – – Gaps Sharp edges Spokes Shepherding satellites

Saturn’s Rings

Enceladus Above the Rings

Spokes on the Rings

Scale Model of Saturnian System

Rings of the Gas Giants