Jupiter and Its Moons History and Interior of Jupiter Accreted as gas giant (H 2, He) Gaseous atmosphere, underlain by liquid, with small core Interior heat generated by gravitational collapse? Trace compounds Fluid molecular Hydrogen Transition zone Fluid metallic hydrogen Possible core Cloud tops aerosols Ammonia crystals Ammonium hydroxide clouds Ice crystal clouds Water droplets 20Mm 40Mm 60Mm Jupiter s Atmosphere Various Prominent Banded Features Pronounced zonal winds, eddies White ovals, brown blebs, streaks, bands Great Red Spot cyclonic feature Great Red Spot white ovals Brown blebs Great Red Spot eddies 1
Jupiter s Gravity Comet Shoemaker-Levy 9 Broken into fragments by Jupiter s gravity in 1992 Each fragment impacted Jupiter s surface in 1994 Chains of impacts also observed on moons Impact of Fragment G Jul 18 1994 Jupiter and Comet Shoemaker -Levy 9 Jupiter s Moons 17 Moons and a Ring System Range of Distances, Sizes, and Orbital Periods: 128-24,200 x 10 3 km (Moon = 384) 20km - 5,276km (Moon = 3476km) 0.3-774 days (proportional to distance) Galilean satellites: Size Distance Name (km) (10 3 km) Callisto Europa Ganymede Callisto 4,880 1,883 Europa 3,126 671 Ganymede 5,276 1,070 Io 3,629 422 Io 2
Jupiter s Moons: Io History and Features of Io Heated by tidal forcing caused loss of icy mantle? Volcanically active Density: ~3.5g/cm 3 Atmosphere: 90% sulfur Composition: silicates sulfur iron volcano and lava plain sulfur, rock mantle Fe, rock core Jupiter s Moons: Europa Features of Europa Ice crust with cracks stressed and heated by tidal forcing evidence of ice volcanism ice movement in plates? Rocky interior and core Density: ~3.0g/cm 3 No atmosphere Liquid water below ice surface? viable environment for life? focus for astrobiological studies cracked surface refrozen ice flows 3
Jupiter s Moons: Ganymede History of Ganymede Surface features older cratered dark regions (40%) younger light grooved terrain from faulting and water release (60%) Metallic core (400-1500km) Density: ~1.9g/cm 3 grooved terrain ice crust metallic core water/ice mantle cratered dark region tectonic features old terrain Jupiter s Moons: Callisto History of Callisto Geologically inactive crust frozen at formation highly cratered (maximal density) no signs of tectonism Interior partially differentiated? or homogeneous, never molten low abundance of radioactive isotopes little tidal forcing Density: ~1.9g/cm 3 mixture of rock and ice Valhalla crater 4
Galilean Moons: Comparisons Io Europa Ganymede Callisto Saturn, Its Moons and Rings History and Interior of Saturn Accreted as gas giant (H 2, He) Gaseous atmosphere, with interior largely liquid, plus small core and mantle Interior radiates heat from internal heat source (gravitational collapse?) 5
Interior of Saturn Characteristics of Core Formed by accretion and gravitational collapse? Iron core surrounded by liquid H 2 and ice? Sequential formation of core by aggregation and separation Possible composition of interior Features of Saturn General Characteristics and Surface Low density (0.7 g/cm 3 ) Fast rotation (10-11 hours) Bands, anticyclones, storms around great white spot High velocity winds (up to 1800 km/hr?) Aurora in upper atmosphere white spot anticyclone (size of Earth) aurora 6
250 0.1 200 150 0.5 altitude (km) 100 1 pressure (bar) H 2 O ice? 10 7
Saturn s Moons General Characteristics 19 moons named, most are icy (densities 1-1.5 g/cm 3 ), but may have rocky constituents, cratered Many are locked by tidal forces. Saturn s Moon Titan Characteristics Opaque atmosphere with several layers of haze Primary liquid N 2, with 1% CH 4 Thick smog composed of hydrocarbons? Oceans of CH 4, ethane (C 2 H 6 ) Surface temperature -180 C Titan Variations in Titan s surface 8
Saturn s Moons Major Moons Icy surfaces, with impact craters Mimas impact ~25% of diameter Some shepherd moons stabilize rings Tethys Rhea Mimas Iapetus Uranus Major Characteristics Discovered in 1781 by Herschel Gas giant: hydrogen and helium (1.2g/cm 3 ), also heavier elements Rotational axis 8 off orbital plane Rings (> 5, rock not ice?) and many moons (5 major, 10 smaller), some may be shepherd moons Methane (gives blue color), ethane, acetylene, diacetylene in atmosphere. Surface is -210 C 9
Uranus s Icy Moons Shakespherian Names Miranda, Ariel, Umbriel, Oberon, Titania, Ophelia, Bianca, Cressida, Desdemona, Juliet, Portia, Rosalind, Belinda, Puck, Caliban, Sycorax, Prospero, Setebos, Stephano Miranda is geologically active: tidal forcing? Oberon Miranda Ariel Umbriel Titania Oberon Neptune Major Characteristics Discovered in 1845 Gas giant: H 2, He (1.6g/cm 3 ), also heavier elements Internal heat source Methane (gives blue color) in atmosphere. Surface is -216 C Great dark spot long-lived storm system; winds 1000 km/hr. Faint rings (dust grains?) and two large moons; weak magnetic field Great dark spot 10
Neptune s Moons Triton and Nepeid Triton: comparable in size to Earth s Moon Retrograde motion around Neptune (captured?) Thin atmosphere (mostly N 2 ) and polar ice cap of solid N 2 Giant faults on surface Volcanoes of N 2 ice vent through surface of CH 4 ice? Nepeid: highly eccentric orbit (captured asteroid?) Triton Pluto Major Characteristics Discovered in 1930 by Tombaugh Smaller than the Moon, about 20% the size of the Earth Irregular orbit, tilted at 17, rotation rate about 6.5 days One moon - Charon (discovered 1978 by Christy) Surface is -240 C Planet or Kuiper belt object (One of 200,000,000 comets) 11