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Where is this?

Explore the fascinating dynamics of Saturn's rings, which are 300,000 km wide and 10 m thick. These rings are made up of shiny snowballs of H2O and were likely formed by Saturn's Roche limit crossing. Learn about the major and minor rings, divisions, ringlets, and the significant roles played by moons like Mimas and Enceladus. Understand the tidal forces that shape the Saturn system and the concept of the Roche limit in ring systems.

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Where is this?

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  1. Where is this?

  2. Where is this?

  3. Dynamics II

  4. Saturn’s Rings 300,000 km wide X 10 m (!) thick

  5. particles forced into plane by orbits albedo 0.8 … shiny snowballs of H2O total mass only that of small moon young … likely formed by Roche limit crossing Saturn’s Rings

  6. 7 major rings … 2 divisions … 1000s of ringlets ABC rings seen from ground … major DEFG rings seen from Voyager/Cassini … minor Cassini Division Mimas 2:1 resonance Encke Division Pan within A ring A ring Atlas on edge (in 3:2 with Mimas) F ring (braided) shepherds Prometheus + Pandora E ring Enceladus volcanism (outside Roche) G ring Mimas drives lump of grinding dust spokes collisions in rings

  7. The Saturn System

  8. Saturn’s Rings Details Pan Pandora

  9. Tides tides are a differential gravitational force~ 1 / r3 cause bulk motions of fluid components ocean tides, moonquakes, Io volcanoes 2 reasons --- bulge amplitude changes, position of bulge changes b. cause torques(~1 / r6) that lead to rotational changes Earth day lengthening, Pluto-Charon locked, Mercury 3:2 spin:orbit resonance eccentric orbit…Mercury elongation…resonance c. cause shape changes if tidal force > tensile strength/self-gravity evidence for Moon’s shape --- closer in the past d. likely creates rings

  10. Tidal Forces 2 x G m2 F tidal≈ ______________ r3 r is distance between two bodies x is distance from center of stressed body Earth-Moon tidal force is 81 X Moon-Earth tidal force Jupiter-Io tidal force is 20,000 X Moon-Earth tidal force

  11. Tides in Earth-Moon System angular momentum is conserved, but … can be swapped between rotation and revolution via tidal torques on Earth: twice per 25 hours due to Moon twice per 24 hours due to Sun (1/2 strength) on Moon: mostly fixed because of synchronous rotation but not entirely because of eccentricity … nutation bulge torque: Earth rotates faster than Moon orbits Earth not perfectly elastic, so bulge not on Earth-Moon line Moon pulls back on bulge --- Earth slows down Earth bulges pull on Moon --- torque acc. Moon outward ~ 1/r6 death spirals: moons moving retrograde, or faster than planet rotates

  12. Moon’s Shape bulge frozen at 2/3 current Moon distance

  13. Roche Limit Roche limit: point beyond which an object is ripped apart by tidal forces aRoche = 2.456 Rp (ρp/ρs)1/3 moons inside Roche limit !?!?! Jupiter has 3 + Saturn has ~ 0 Uranus has 8 + Neptune has 4 + assumes fully deformable (fluid) moon (2) assumes no “tensile strength” … moving inward, resulting orbital systems have … … large moons … small moons … ring particles

  14. Roche Limits and Ring Systems

  15. Neptune’s Rings Adams Lassell LeVerrier Galle

  16. Billions of Years from Now…

  17. Jupiter’s Rings

  18. Jupiter’s Rings Details

  19. Jupiter’s Rings Details

  20. Solar System Explorers 03 Describe something you have already learned in this course that you did not know previously. 1. The Moon has a tenuous (good word!) atmosphere 2. Voyager 2 is the only spacecraft to visit Uranus and Neptune … now beyond 100 AU. 3. Titan has methane seas. 4. Largest structure in SS is Jupiter’s magnetotail 5. Earth would survive longer if we booted it out of SS 6. TNOs are beyond the orbit of Neptune … and there are many other categories. 7. Venus has a retrograde rotation. 8. Coldest place in SS is Triton at 38K. 9. Mars has araneiform terrain … and sublimation causes it. 10. IRAS has SIGNIFICANT !!! stellar information … galaxies are stupid. 11. Tholins are compounds organic compounds on Titan (primarily). 12. Moon orbits the Sun NOT THE EARTH. 13. Magnetic fields of ice giants are not centered. 14. Planets must be in hydrostatic equilibrium. 15. Jupiter is so massive is more than twice all other planets. 16. Earth is blue because of Rayleigh scattering and H2O reflectivity. 17. Fusing of deuterium vs. hydrogen separates stars from brown dwarfs. 18. Surface magnetic fields of giant planets not that different from Earth’s. 19. Rhea may have rings … but probably not. 20. Uranus has a moon named OBERON.

  21. Solar System Explorers 04 How does the Sun affect objects in the Solar System? 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20.

  22. …………………………

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