Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Eight Worlds wikipedia , lookup
Exploration of Io wikipedia , lookup
Earth's rotation wikipedia , lookup
Late Heavy Bombardment wikipedia , lookup
Exploration of Jupiter wikipedia , lookup
Jumping-Jupiter scenario wikipedia , lookup
History of Solar System formation and evolution hypotheses wikipedia , lookup
Where is this? Where is this? Solar System Explorers 02 1. What three ices dominate the ice giants’ composition (that is ice)? 2. What is the mass ratio of Jupiter to Saturn, 30:1, 10:1, or 3:1? 3. Which two planets do not have internally generated magnetic fields today? 4. What technique is the best for measuring the masses of the Jovian planets and their moons? 5. Do protoplanetary disks last roughly 105, 107, or 109 years? B. Name any moon of Uranus. Solar System Explorers 02 Solar System Explorers 02 1. What three ices dominate the ice giants’ composition (that is ice)? CH4, NH3, H2O 2. What is the mass ratio of Jupiter to Saturn, 30:1, 10:1, or 3:1? 3:1 3. Which two planets do not have internally generated magnetic fields today? Venus and Mars 4. What technique is the best for measuring the masses of the Jovian planets and their moons? spacecraft tracking data 5. Do protoplanetary disks last roughly 105, 107, or 109 years? 107 years B. Name any moon of Uranus. Juliet, Portia, Puck, Miranda, Ariel, Umbriel, Titania, Oberon … Dynamics II Saturn’s Rings 300,000 km wide X 10 m (!) thick 7 particles forced into plane by orbits albedo 0.8 … shiny snowballs of H2O Saturn’s Rings total mass only that of small moon young … likely formed by Roche limit crossing 8 6 major regions … 2 divisions … 1000s of ringlets ABC rings seen from ground … major DEFG rings seen from Voyager/Cassini … minor Cassini Division Encke Gap Mimas 2:1 resonance Pan within A ring A ring F ring (braided) E ring G ring spokes Atlas on edge (in 3:2 with Mimas) shepherds Prometheus + Pandora Enceladus volcanism (outside Roche) Mimas drives lump of grinding dust collisions in rings The Saturn System Saturn’s Rings Details Pan Pandora 11 Tides tides are a differential gravitational force ~ 1 / r3 a. 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. likley creates rings Tidal Forces 2 x G m2 F tidal ≈ ______________ r3 r is distance between two bodies x is distance from center of stressed body tides on Earth m2 (kg) r (km) Ftidal/2RG Sun 1.99e30 1.50e08 5.90e05 Venus 4.87e24 4.14e07 6.86e01 Moon 7.35e22 3.84e05 1.30e06 Jupiter 1.90e27 6.29e08 7.63e00 Winner! 2.2 X Sun Earth-Moon tidal force is 81 X Moon-Earth tidal force Jupiter-Io tidal force is 20,000 X Moon-Earth tidal force 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 Moon’s Shape bulge frozen at 2/3 current Moon distance 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 + (1) assumes fully deformable (fluid) moon (2) assumes no “tensile strength” … moving inward, resulting orbital systems have … … large moons … small moons … ring particles Roche Limits and Ring Systems 17 Neptune’s Rings Adams Lassell LeVerrier Galle Billions of Years from Now… Jupiter’s Rings 20 Jupiter’s Rings Details Jupiter’s Rings Details 22 Solar System Explorers 03 Describe something you have already learned in this course that you did not know previously. 1. clathrates are ices with molecules inserted into ice structure 2. storm on Neptune is a downwelling compared to Jupiter’s GRS upwelling 3. Titan has magic islands on its mare that appear/disappear 4. spacecraft flybys yield information about both mass and mass distribution of worlds 5. Nice Model explains 6. beta Pic disk can be seen because of double-peaked SED 7. gas giants have faster rotations than terrestrials because of conservation of angular momentum 8. Uranus and Neptune have off-center magnetic fields 9. Triton is the only LARGE moon that orbits retrograde 10. Triton was likely captured explaining why it orbits retrograde 11. a proplyd is a protoplanetary disk 12. Sun spins faster at equator than pole because convection cells push in different directions 13. Mercury spins strangely because of a 3:2 spin/orbit resonance (eccentric orbit) 14. methane makes Uranus 2% blue and Neptune 3% bluer 15. … that is why they have similar equilibrium temps 16. Centaurs exist! and are divided into active and inactive subgroups 17. it should be called the Asteroid Comb 18. Antarctica is a good place to find meteorites 19. Jupiter’s magnetotail extends to Saturn’s orbit 20. the answer to most questions is TEMPERATURE (once in awhile, GIANT IMPACT) 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. …………………………