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Outline Jupiter Saturn, its rings and moons Uranus Neptune Dwarf planets Jovian – Jupiter like Planets Four outer planets Known as the ‘gas giants’ o Two are ‘liquid giants’ o Two are ‘ice giants’ Each has rings Each has many moons Great Red Spot Great Red Spot Turbulence White ovals within the bands Weather on Jupiter Jupiter’s Interior Jupiter’s Interior Magnetic Field Aurora Comet impact, July 1994 Jupiter’s Ring This image was taken by the Galileo satellite with Jupiter in shadow Enhanced color image of the halo around the ring Ring particles are micron-sized (cig. smoke) The ring is formed from particles released from satellites due to micro-impacts Particles continually fall into the ring on the outer edge and into Jupiter on the inner edge Jupiter moons to scale Io Europa Ganymede Callisto Moons of Jupiter Io Europa Ganymede Callisto Ganymede, the largest moon in the solar system, is 8% larger than Mercury and is 52% larger than the Moon Ganymede – largest moon a) Enhanced color b) True color, showing evidence of water Density 1.9g/cm3, mix of rock and ice Callisto close-up Callisto has a mineral-rich liquid water ocean under its surface These craters show the clean ice underneath the dirty surface. Density 1.79g/cm3, 50:50 rock to ice Europa Density of 3g/cm3, mostly rock, with an icy surface Notice the cracks, which help indicate a liquid ocean underneath Cracked, icy crust of Europa The color is brown, due to the minerals dissolved in the liquid water beneath the 100 km thick icy crust Io Most volcanically active object in the solar system, ~100 active volcanoes Density 3.55g/cm3, no ice, just metals and rock Saturn Size of the rings Geology of the rings Cassini’s division is caused by resonance Particles in the different rings vary in size Thinness of the rings The plane of the rings is only about a dozen meters thick Shepherd satellites keep dust in this and the next ring Without the moons, there would be no rings around any planet Cassini images Cassini images Saturn’s Interior Saturn’s Moons 53 Named moons and over 150 ‘moonlets’ Titan Titan IR image Enceladus There is liquid water underneath the surface A geyser on the south pole is emitting water into space, adding to the E ring and recovering the surface Enceladus’ geyser Enhanced views of Enceladus’ geyser Quiz Time! 1 Jupiter reveals all of the following except A. Auroras and lightning. B. A powerful magnetic field. C. Radiation belts of solar wind particles. D. A solid surface beneath the clouds. 2 Jupiter’s ineterior: A. Is mostly molten magma. B. Is mostly liquid hydrogen. C. Is mostly gas. D. Is mostly ice. 3 Jupiter’s Great Red Spot is: A. A large volcano on Jupiter’s surface. B. Evidence of life on Jupiter. C. A cyclonic storm. D. One of Jupiter’s polar caps. 4 Jupiter’s four Galilean moons are: A. Zeus, Jove, Eros, and Appalonia. B. Io, Europa, Ganymede, and Callisto. C. Micky, Minnie, Goofy, and Doc. D. Castello, Eros, Ganymede, and Io. 5 Jupiter’s moon Io has: A. Lots of Geysers. B. Nothing but ice covering it. C. Methane oceans. D. Lots of Volcanoes. 6 What theory was advanced to explain the origin of Saturn's rings? A. Another planet wandered too close, invaded the Roche limit, and broke up. B. Saturn captured material from the Asteroid Belt. C. Comets collided with and broke up small satellites that formed with the planet. D. They are basically the same today as they were when they first formed with Saturn. 7 Saturn’s rings: A. Are unique; only Saturn has rings. B. Two planets have rings, Saturn and one other. C. Four planet have rings. D. All planets have some sort of rings. 8 The thickness of Saturn’s rings is: A. A few meters. B. A couple of miles. C. Hundreds of kilometers. D. Close to 10% of an AU. 9 Saturn’s has: A. No moons, just rings. B. Only shepard moons; they keep the rings together. C. Four moons. D. More than 100 moons. 10 Saturn’s moon Enceladus: A. Shoots lightning at Saturn. B. Has volcanoes that shoot rocks. C. Is dormant and quiet. D. Has a giant geyser that rains ice. Uranus’ rings – found when occulting a star, in 1977 Notice the eccentricity of the ε ring, probably due to the eccentricity of its shepherd moons, Ophelia and Cordelia These rings have an albedo of 0.015, darker than coal • There is almost no dust, just boulder-sized particles Uranus’ moon Ariel Perhaps these canyons were cut by flowing water (1160 km) Uranus’ moon Miranda Notice both the deep gauging and the round sunken sections, possibly due to convection as the moon was cooling (485 km) The most common image of Neptune (The spot is no longer visible.) Neptune is 4% smaller than Uranus. Neptune’s seasons Neptune’s seasons Neptune’s rings aren’t complete, but have voids They are much dustier than Uranus’ rings There aren’t enough particles to complete the circles of the rings in Neptune. Neptune’s moon Triton (78% Earth’s Moon) Nitrogen frost polar cap (above) and a basin showing signs of flooding Planetary Line-up by Lynette Cook, picture used by permission Planetary Line-up by Lynette Cook, picture used by permission Planetary Revolutionary Periods and Distances Mercury – 0.24 yrs – 0.387 AU Venus – 0.62 yrs – 0.723 AU Earth – 1 yr – 1 AU Mars – 1.88 yrs – 1.52 AU Jupiter – 11.87 yrs – 5.20 AU Saturn – 29.46 yrs – 9.54 AU Uranus – 84.01 yrs – 19.2 AU Neptune – 164.79 yrs – 30.1 AU The Definition of a planet A "planet" is defined as a celestial body that: 1. Is in orbit around the Sun 2. Has sufficient mass for its self-gravity to assumes a nearly round shape 3. Has cleared the neighborhood around its orbit Dwarf Planet Candidates Pluto and its three moons Charon, Hydra and Nix Charon’s orbit Charon, Pluto’s largest moon is about 51% of its size, but only 1/12 the mass Dwarf Planets and the Kuiper Belt The Kuiper Belt is a region of perhaps 70,000 asteroid-like part rock, part icy bodies close to Neptune’s orbit. About 1000 have been found, to date. Eris is so far the largest (about 5% larger), followed by Pluto, then Sedna and Orcus (~65% Pluto’s size), then Quaoar (~50%) With Ceres (in the asteroid belt), these are the dwarf planets. Plutinos and the Kuiper Belt The Kuiper belt dwarf planets are in different resonances with Neptune Pluto and the ~ 100 other, smaller Plutinos are in a 3:2 resonance. (For every 2 orbits of Plutinos, Neptune has 3 orbits. This is why Pluto will never hit Neptune, even though it crosses Neptune’s orbit.) Other objects have many other resonances (2:1, 4:3, etc).
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