Download Saturn Moons - Department of Geology UPRM

GEOL 3045: Planetary Geology
Lysa Chizmadia
Saturn’s Satellites
Introduction
 At least 60 moons
 Classification of Moons:
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A-ring Moonlets
Ring Shepherds
Co-orbitals
Inner Large Moons
Image from: http://solarsystem.nasa.gov/planets/
profile.cfm?Object=Saturn&Display=Moons
 Alkyonides
 Trojans
– Outer Large Moons
– Irregular Moons
 Inuit Group
 Norse Group
 Gallic Group
Image from: http://en.wikipedia.org/wiki/Saturn
A-ring Moonlets
 4 discovered in 2006 by
Cassini
– 8 more discovered in 2007
 Tiny moons inside the A-ring
– Diameters: 0.06 to 0.14 km
 Probably formed due to
shattering of inner satellite
during impact
 Discovered by propellershaped disturbances in ring
Photo Credit: NASA
Image from: http://www.theregister.co.uk/2007/10/25/moonlets_a_ring/
Ring Shepherds
Pan in Encke Division
 Orbit within or just outside
rings
 Sculpt the rings
Image from:http://en.wikipedia.org/wiki/Pan_%28moon%29
– Giving them sharp edges & gaps
 5 named & 3 unconfirmed
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Prometheus (left) & Pandora (right) in Saturn’s F-ring
Ripples caused by Daphnis
Pan
Daphnis
Atlas
Prometheus Image from: http://en.wikipedia.org/
wiki/Daphnis_%28moon%29
Pandora
S/2004 S3, S/2004 S4, S/2004 S6
Image from: http://en.wikipedia.org/wiki/Shepherd_satellite
Co-orbitals
 Epimetheus & Janus
 Orbit differs by only 50 km
 Inner orbits are faster so must
approach each other
 When inner moon catches
outer moon, gravitational
attraction boosts inner’s
momentum, increasing orbit
 Opposite happens to outer
moon
 Thus, they trade places when
they pass each other
Images from: http://en.wikipedia.org/wiki/
Epimetheus_%28moon%29
Epimetheus
Janus
Image from: http://en.wikipedia.org/wiki/
Janus_%28moon%29
Inner Large Moons
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Mimas (Herschel crater)
Methone
Anthe
Pallene
Enceladus *
Tethys
Mimas
http://en.wikipedia.org/wiki/Mimas_%28moon%29
Dione
– Telesto (L4)
– Calypso (L5)
 Dione (ice cliffs)
– Helene (L4)
– Polydeuces (L5)
http://en.wikipedia.org/wiki/Dione_%28moon%29
Enceladus
 Ice ridges & Cryovolcanism
Images from: http://en.wikipedia.org/wiki/Enceladus_%28moon%29
Outer Large Moons
Rhea
 Rhea
Hyperion
– Homogeneous interior
– 2 adjacent large craters
– Possible ring system
 Titan *
 Hyperion
– Chaotic rotation
– Sponge-like texture
Image from: http://en.wikipedia.org/wiki/Rhea_%28moon%29
Image from: http://en.wikipedia.org/wiki/Hyperion_%28moon%29
Iapetus
Iapetus
 Iapetus
– 2 tone coloration
– High inclination
– Equitorial ridge
Images from: http://en.wikipedia.org/wiki/Iapetus_%28moon%29
Titan
 Only moon w/ dense atm
– Pressure: 1.6 bars
– 98.4% N2, 1.6% CH3 & H-Cs
– CH3 must be produced
 Not from comets b/c CO
 Not from nebula b/c  He, Ne
 Only body with liquid on
surface
– Other than Earth
– Liquid CH3 lakes
 Diameter: 5150 km
– Mercury: 4879 km
– Moon: 3474 km
Images from: http://en.wikipedia.org/wiki/Titan_%28moon%29
Irregular Moons
 3 main groups
– Inuit Group
– Norse Group
– Gallic Group
Pheobe
Images from: http://en.wikipedia.org/wiki/Phoebe_%28moon%29
Inuit Group
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Prograde irregular satellites
Semi-major axes: 11-18 x 106 km
Inclinations: 40-50 degrees
Eccentricities: 0.15-0.48
Spectral homogeneity
– Similar to Gallic Group
– Break up of single object
 5 members:
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Kiviuq
Ijiiraq
Paaliaq
Siarnap
Tarqeq
Image from: http://en.wikipedia.org/wiki/Ijiraq_%28moon%29
Norse Group
 Retrograde irregular
satellites
 Semi-major axes: 12-42 x
106 km
 Inclinations: 136-175
degrees
 Eccentricities: 0.13-0.77
 Composed of > 4
subgroups
– two i=174 subgroups
– Skathi subgroup
– Narvi subgroup
Image from: http://en.wikipedia.org/wiki/Saturn%27s_Inuit_group_of_satellites
Gallic Group
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Prograde irregular satellites
Semi-major axes: 16-19 x 106 km
Inclinations: 35-40 degrees
Eccentricities: ~0.53
Spectral homogeneity
– Similar to Inuit Group
– Break up of single object
 4 members:
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Albiorix
Bebhionn
Erriapus
Tarvos
Image from: http://en.wikipedia.org/wiki/Ijiraq_%28moon%29
Summary
 At least 60 moons
 At least 6 groups
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A-ring moonlets
Shepherd moons
Co-orbitals
Inner large moons
 Includes Enceladus
– Outer large moons
 Includes Titan
– Irregular Moons
 Inuit group
 Norse group
 Gallic group
 Mimas
– Herschel Crater
 Dione
– Whispy ice ridges
 Enceladus
– Ice ridges ~ Europa
– Cryovolcanism
 Rhea
– Homogeneous interior
– Possible ring system
 Titan
– H-C rich atmosphere
– Liquid HC on surface
 Hyperion
– Sponge-like surface texture
 Iapetus
– Two-tone surface colors
– Equatorial ridge