8. The Outer Planets.pdf

Lesson 8 The Outer Planets Copyright © 2020 W. W. Norton & Company The Giant Planets ▪ They are the outermost four planets consisting of the gas giants, Jupiter and Saturn, and ice giants Uranus and Neptune. Figure 22.19a Jupiter ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ The largest planet Rotates v...

Lesson 8 The Outer Planets Copyright © 2020 W. W. Norton & Company The Giant Planets ▪ They are the outermost four planets consisting of the gas giants, Jupiter and Saturn, and ice giants Uranus and Neptune. Figure 22.19a Jupiter ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ The largest planet Rotates very fast (10-hour day) Produces its own internal heat Atmosphere is primarily hydrogen and helium Color bands come from trace elements and convection. The composition of Jupiter is similar to that of the Sun – mostly hydrogen and helium. Deep in the atmosphere, pressure and temperature increase, compressing the hydrogen gas into a liquid. This gives Jupiter the largest ocean in the solar system – an ocean made of hydrogen instead of water. Atmosphere contains water, methane (CH4), hydrogen sulfide (H2S), ammonia (NH3) and phosphine (PH3) Great Red Spot is a giant storm Strong magnetic field Distance 800 million km from sun(500 million miles) Polar Flattening: 1/16 (Earth = 1/298) Circles Sun in 12 years Mass: 318 Earths Volume: 1321 Earths Density: 1.326 g/cm3 Four large satellites, complex system of moons, rings, and asteroids 95 moons Winds and Storms on Jupiter ▪ The color bands visible on Jupiter come from trace elements and possible upwelling and downwelling regions of the atmosphere from convection. Figure 22.20 Great Red Spot ▪ The Great Red Spot, a giant storm that rotates counterclockwise ▪ The spot is bigger than the Earth though recently it appears to be shrinking. Figure 22.20a,c Jupiter is Hot Inside Pioneer 10 and 11 were first to Jupiter, 1973 Pioneer 10-11, 1972-1974 Voyager I-II 1977-1979 Galileo 1989-1995 Galileo’s Atmospheric Probe Jupiter Movie Jupiter Has a Very Thin Ring The Impact of Comet Schumacher-Levy For the first time ever, in 1994 we witnessed the impact of a comet with a planet. (Infrared) Impact of Comet Schumacher-Levy 9, 1993 Jupiter’s Largest Moons ▪ The outer planets all have large numbers of moons; more are always being discovered. ▪ Jupiter’s four largest moons are spherical and have a number of interesting features. ▪ Io (top left), Europa (bottom left , Ganymede(top right), and Callisto (bottom right) ) Figure 22.21 Ganymede and Europa Interiors ▪ Ganymede may have liquid-water sub-surfaces covering an internal shell of rock ▪ Has dark terrain and light terrain ▪ Europa may have a vast subsurface ocean, where primitive life might inhabit Europa ▪ Ganymede (left) and Europa (right) Figure 22.22 Ganymede: Largest Moon in the Solar System Larger than Mercury Has Magnetic Field (only one of the moons) Grooves on Ganymede – signs of surface movement similar to plate tectonics on Earth? Grooved Terrain on Ganymede Signs of comet impacts? Chains of craters with ejecta Magnetometer data give clue to interior of Ganymede Iron core Ice crust Liquid water Silicate lower mantle Europa Colored bands – fractures in ice crust “Icebergs” on Europa suggest thin (5 – 20 km) crust How do we get heat into the interior of Europa? ▪ Tidal heating. Europa is tugged towards Jupiter, but is also pulled away from Jupiter by Io, Ganymede and Callisto. ▪ Without tidal heating, Europa would look like Callisto. An Eruption on Io Lava Flows on Io ▪ Most volcanically active body in the solar system ▪ Red and yellow colours are sulfur ▪ Volcanic vents are filled with melted silicate rocks Eruption on Io Callisto Valhalla Basin, Callisto - the largest ring crater Thousands of craters at all scales on Callisto Valhalla basin - ~600 km in diameter Details of a “ring” of Valhalla Basin Magnetometer data give clue to interior of Callisto Solid rock-ice Ice-rich outer layer Relative ages of the surfaces of the Galilean Satellites: From left to right, from young to old. Saturn ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ The ringed planet Lowest average density Atmosphere composed primarily of hydrogen (96%) No solid surface Large number (always being added to) of known moons Magnetic field Generates more energy than it receives from the Sun About nine times Earth’s diameter 95 times as massive as Earth 1.4 billion kilometers (900 million miles) from Sun Orbits Sun in 29.5 years Largest moon is Titan (5100 km) 146 moons Density is 0.7 g/cm3 Pioneer 10 and 11 and Voyageur 1 and 2 Saturn and Its Rings ▪ Rings are a system of orbiting particles of ice, dust, pebbles, and even small moons ▪ Composition, density, and particle size vary throughout. Figure 22.23b Cassini ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ Launch: October 15, 1997 Venus Flyby April 26, 1998 Venus Flyby June 24, 1999 Earth Flyby August 18, 1999 Jupiter Flyby December 30, 2000 Saturn Orbit Insertion July 1, 2004 Huygens Probe Separation Dec. 24, 2004 Titan Landing January 14, 2005, made measurements of Titan’s atmosphere, lasted 4 hours Atmosphere is CO2 and light winds, temperature of -170 oC Saturn’s South Pole Storms in Saturn’s Far North Saturn’s Moons ▪ Saturn has a large number of moons (146). ▪ Recent results (2019) bring the total to the highest in the Solar System. Figure 22.24a Enceladus ▪ One of the discoveries of the Cassini mission are waterice jets that erupt from the surface of Enceladus. ▪ Tiger strips are tectonic fractures. Figure 22.24b Enceladus Enceladus Enceladus up close and Personal Titan ▪ Only moon in Solar System with an atmosphere (mostly nitrogen) ▪ Huygens probe suggested presence of methane clouds ▪ Mapping shows hydrocarbon (methane and ethane) lakes, active volcanic vents, and huge dune possibly of frozen methane grains. ▪ Most Earthlike object in Solar System for the type of surface and atmospheric processes that occur, though at very cold temperatures Aerial View of Titan Surface of Titan Lakes on Titan Titan’s Largest Sea Uranus ▪ Axis of rotation tilted 98 degrees, almost parallel to orbital plane ▪ Color comes from methane in atmosphere ▪ Ice giant where significant part of interior made of water ice ▪ Rocky metallic core ▪ Similar in size and composition to Neptune ▪ Density is 1.27 g/cm3 ▪ Voyager 2 made its closest approach to Uranus on January 24, 1986, coming within 81,500 km, picture right Figure 22.25a Uranus ▪ The planet appeared to have few features but Voyager 2 found evidence of an ocean of boiling water about 500 miles (800 kilometers) below its cloud tops, 10 new moons and 2 new rings. ▪ About 4 times diameter of Earth ▪ 3 billion km (1-3/4 billion miles) from Sun ▪ 84 Years to Circle Sun ▪ Rotates in 16 hours ▪ Five large satellites (5001500 km), ten smaller ones ▪ Nine narrow rings ▪ 27 moons Figure 22.25a The Rings of Uranus ▪ Although all four giant planets have rings (Uranus’s below), only Saturn’s are easily visible. Figure 22.26a Moons of Uranus ▪ The five largest moons of Uranus are all smaller than the Earth’s Moon and appear to be composed of ice and rock. ▪ Example: Titania Figure 22.27a Oberon Umbriel Ariel Miranda Neptune ▪ Very similar in size and composition to Uranus ▪ About 4 times diameter of Earth- a bit smaller than Uranus ▪ 4.5 billion km (2.8 billion miles) from Sun ▪ 165 Years to Circle Sun ▪ Rotates in 18 hours ▪ One large satellite (2700 km), seven smaller ones ▪ Four narrow rings ▪ Color comes from methane ▪ Has active atmosphere with bands, streaks, and storms ▪ 14 moons ▪ Density is 1.64 g/cm3 Figure 22.25b Rings of Neptune ▪ The planet itself has been blacked out in this image, so that its brightness doesn’t mask the faint rings. Figure 22.26b The Great Dark Spot Neptune and Triton Moons of Neptune ▪ Has a number of moons, the largest of which is Triton, which orbits retrograde ▪ Note the relatively few numbers of craters on its icy surface as compared to other bodies. ▪ Has a thin atmosphere of methane and nitrogen ▪ May have liquid water ocean beneath its surface Figure 22.27b Outer Planets Structure Metallic Hydrogen is hydrogen which undergoes a phase transition to a metallic, pressure-ionized state. Its electrons are not bounded to one nucleus but move around nuclei such as in metals In giant planets, this metallic hydrogen is fluid, not solid. It is conductive and 35 x more explosive than TNT Figure 22.27b Homework ▪ Complete Planet Chart in D2L, use the videos/Nasa link/power points to understand the planets and their moons Figure 22.27b