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Giant Planets Neptune QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Uranus Saturn Jupiter © 2005 Pearson Education Inc., publishing as Addison-Wesley Important Notes: • Read Chapter 11: “Jovian Planet Systems” • Homework #8 due Friday (on today’s and Thursday’s lecture) • Mars: Mark mid-semester position! • Midterm #2: Tuesday, April 15 © 2005 Pearson Education Inc., publishing as Addison-Wesley Terrestrial (Rocky) Outer 4 Planets: Gaseous Giants The Solar System © 2005 Pearson Education Inc., publishing as Addison-Wesley The 4 “Giant Planets” “Jovian Planets”: • No solid surfaces !!! Jupiter Much higher mass & radius than Earth, Venus, Mars. Saturn Uranus and a QuickTime™ andQuickTime™ a & He H & He decompressor TIFF (Uncompressed) H2O, TIFFH(Uncompressed) decompressor are needed to see this picture. (most common H & He are needed to see this picture. atoms in universe) Neptune H2O, H & He (text: “hydrogen compounds” = water, methane, ammonia) “Ice Giants” All have Rock Cores: 10-15 Earth-Masses © 2005 Pearson Education Inc., publishing as Addison-Wesley Next Lecture: Moons orbiting the Giant Planets QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Jupiter’s Moon: Io © 2005 Pearson Education Inc., publishing as Addison-Wesley • A volcanic explosion can be seen silhouetted against dark space over Io's brilliant limb. Io more volcanically active than Earth. Jupiter – King of the Planets Mass = 0.001 solar (318 earths), Radius = 11.2 Earths, Density = 1.3 g/cc (1.3 x water) Distance: 5.2AU Orbital Period: 11.8 years Rotation period: 9.9 hours. Flattened Spheroid © 2005 Pearson Education Inc., publishing as Addison-Wesley Saturn Mass = 95 Earths Radius = 9.4 Earths Density = 0.7 gram/cm3 (floats) Distance: 9.5 AU Orbital Period: 29.4 years Rotation period: 10.6 hours. © 2005 Pearson Education Inc., publishing as Addison-Wesley Rings: Composed of billions of icy-rocks and icy dust (water and silicates). UranusOrbital Period: 84 years; Mass = 14.5 Earths Radius = 4.0 Earths Density = 1.3 gram/cm3 = 1.3 x water Distance: 19.2 AU Rotation period: 17.2 hours. Visible Light •Featureless in visible light, because clouds are below haze layer of methane (colder than Saturn). © 2005 Pearson Education Inc., publishing as Addison-Wesley Infrared Light (Thermal Emission) Neptune © 2005 Pearson Education Inc., publishing as Addison-Wesley Neptune Mass = 17 Earths Radius = 3.9 Earths Density = 1.76 x water Distance: 30 AU Orbital Period: 163 years; Rotation period: 16.1 hours. Cyclonic storms. © 2005 Pearson Education Inc., publishing as Addison-Wesley GIANT PLANETS © 2005 Pearson Education Inc., publishing as Addison-Wesley Spacecraft Reconnaisance 1980’s: Voyager 1 & 2 QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Camera Spectrometer Measures spectral lines: Chemical composition QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. © 2005 Pearson Education Inc., publishing as Addison-Wesley Visit all 4 giant planets Spacecraft Reconnaisance; Galileo Spacecraft QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. •Launched from Space Shuttle 1989 QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIF F (Uncompressed) decompressor are needed to see this picture. © 2005 Pearson Education Inc., publishing as Addison-Wesley Spacecraft Reconnaisance; Arrived: 1995 Galileo Spacecraft QuickTime™ and a TIF F (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. 2003: Dropped into Jupiter’s Atmosphere: Measure Chemical Composition: 97% hydrogen & helium Plus 3% C, N, O, S, Si … © 2005 Pearson Education Inc., publishing as Addison-Wesley Giant Planet’s Chemical Composition Mostly Hydrogen and Helium •Add H to: C, N, O C, N, O, H Chemistry © 2005 Pearson Education Inc., publishing as Addison-Wesley Why are the Jovian Planets Massive and Gaseous (H, He) ? • Formed beyond the frost line (3 AU): so cold that ice particles exist with silicate dust. • Ice and Dust collides, sticks grows into icy-rocky core. • Core’s gravity captures H/He gas • Planet attracts ices and dust that orbit • Moons formed out of these disks: A miniature solar system. Young Solar System: Gas & Dust Young Jupiter © 2005 Pearson Education Inc., publishing as Addison-Wesley Quiz If Jupiter formed in a protoplanetary disk that had twice as much dust it: a) Would have a bigger core b) Might have more hydrogen c) Might have more metallic hydrogen d) All of the above © 2005 Pearson Education Inc., publishing as Addison-Wesley QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. © 2005 Pearson Education Inc., publishing as Addison-Wesley • Color Enhancement QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. © 2005 Pearson Education Inc., publishing as Addison-Wesley QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. © 2005 Pearson Education Inc., publishing as Addison-Wesley Hydrostatic Equilibrium: Pressure balance Pressure at any depth = gravitational weight of column above “Hydrostatic equilibrium” governs the structure of all planets. The inside has higher pressure and density because of the weight of the overlying material. © 2005 Pearson Education Inc., publishing as Addison-Wesley Inside Jupiter • Jupiter emits almost twice as much energy as it absorbs from the Sun. • accretion, differentiation, radioactivity can not account for it • Jupiter must still be contracting • Jupiter has 3 x more mass than Saturn, but is only slightly larger in radius! • the added weight of H & He compresses the core to a higher density • like stacking pillows © 2005 Pearson Education Inc., publishing as Addison-Wesley • If Jupiter had 10x its mass, it would have same radius ! Add even more mass, and Jupiter would get smaller ! • Jupiter is about as large as a planet can get. • Uranus & Neptune have less mass than Saturn, yet they have higher densities • They must be made of denser material: • Rock & Ice ! Quiz On the moon, a cup of sugar has some pressure, P, at its bottom. You add 50% more sugar to the cup. The new pressure at the bottom is: a) b) c) d) 0.5 P 1.0 P 1.5 P 2.0 P © 2005 Pearson Education Inc., publishing as Addison-Wesley Inside Jupiter No solid surface and consists mostly of H & He. Distinct interior layers, defined by increasing density inward. • Moving from the surface to the core: • temperature increases • pressure & density increases • Hydrogen atoms so dense: Electrons not associated with any one atom: Free- electrons. Metallic Hydrogen! • Jupiter's core is rock & ice: ~10 times the mass of Earth. . . . Controversial. © 2005 Pearson Education Inc., publishing as Addison-Wesley Inside the Jovian Planets • All Jovian cores appear to be similar. • made of rock, metal, and Hydrogen compounds • 10 x the mass of Earth • Uranus & Neptune captured less gas from the Solar nebula. • accretion of planetesimals took longer • not much time for gas capture before nebula was cleared out by Solar wind • Only Jupiter and Saturn have high enough pressure for H & He to exist in liquid and metallic states. © 2005 Pearson Education Inc., publishing as Addison-Wesley Rotational Distortion of Planet’s Shape Centrifugal Force: Flings material at equator outward Due to Rotation © 2005 Pearson Education Inc., publishing as Addison-Wesley Determining the Density inside a Rotating Planet Use Motion of Orbiting Satellites Rotation flattens shape —> Less pull on satellite at poles Higher density toward center —> Exerts Point-like Grav. Force Track acceleration of satellites accurately —> Density throughout interior © 2005 Pearson Education Inc., publishing as Addison-Wesley - Another Effect of Planet’s Rotation - The Great Red Spot QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. © 2005 Pearson Education Inc., publishing as Addison-Wesley Great Red Spot A Hurricane that has lasted 300 years QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. © 2005 Pearson Education Inc., publishing as Addison-Wesley Cyclonic Motions Southern Hemisphere Northern Hemisphere © 2005 Pearson Education Inc., publishing as Addison-Wesley Coriolis effect: Motion from High Pressure area Jovian Storms • Red Spot: A High Pressure Storm • Analogous to hurricanes, but they rotate in the opposite direction • Jupiter • the Great Red Spot • we are not sure why it is red • Neptune • the Great Dark Spot © 2005 Pearson Education Inc., publishing as Addison-Wesley Planet Rotation Neptune’s Storms scooter © 2005 Pearson Education Inc., publishing as Addison-Wesley Quiz You are standing on the equator of the Earth and you throw a ball fast, directly toward the south pole. The ball’s trajectory will a) b) c) d) Carry it toward the south pole Veer to the right Veer to the left Curl around in a spiral © 2005 Pearson Education Inc., publishing as Addison-Wesley Altitude above clouds tops (km) Jupiter’s Cloud Layers • Convection in the troposphere causes Jovian weather. • Warm gas rises to cooler altitudes, where it condenses to form clouds. • Three gases condense in the Jovian atmosphere: • ammonia (NH3) • ammonium hydrosulfide (NH4SH) • water (H2O) • They condense at different temperatures, so their clouds form at different altitudes. Temperature (C ) © 2005 Pearson Education Inc., publishing as Addison-Wesley The Jovian Atmospheres • The temperature profile of each planet determines the color of its appearance. • Cloud layers form where a particular gas condenses. • Saturn has the same cloud layers as Jupiter. • they form deeper since Saturn is colder overall • they are spread farther apart since Saturn has lower gravity • Uranus & Neptune • cold enough to form methane clouds © 2005 Pearson Education Inc., publishing as Addison-Wesley Bands of Jupiter What Causes them? © 2005 Pearson Education Inc., publishing as Addison-Wesley Convection on Jupiter: •Warm air rises •Coriolis force diverts path sideways Coriolis force is due to rotation of planet •Jupiter rotates fast: Period = 10 hours © 2005 Pearson Education Inc., publishing as Addison-Wesley Wind Speed in Jupiter’s Bands •1000 km/hr © 2005 Pearson Education Inc., publishing as Addison-Wesley Winds of Jupiter’s Bands Red Spot in Southern Hemisphere © 2005 Pearson Education Inc., publishing as Addison-Wesley Jupiter Uranus Magnetic Fields Neptune © 2005 Pearson Education Inc., publishing as Addison-Wesley Saturn Jupiter's Magnetosphere QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. © 2005 Pearson Education Inc., publishing as Addison-Wesley • Ion and neutral mass spectrometer instrument on the Cassini spacecraft, makes the huge magnetosphere surrounding Jupiter visible. The magnetosphere is a bubble of charged particles trapped within the magnetic environment of the planet. In this picture, a magnetic field is sketched over the image to place the energetic neutral atom emissions in perspective. • Also shown for scale and location are the disk of Jupiter (black circle) and the approximate position (yellow circles) of the doughnut-shaped torus created from material spewed out by volcanoes on Io, one of Jupiter's large moons. Jupiter’s Magnetosphere – Bigger than the Sun Solar Wind protons & electrons © 2005 Pearson Education Inc., publishing as Addison-Wesley Jovian Magnetospheres • Saturn, Uranus, & Neptune have smaller & weaker magnetospheres. • fraction of electrically conducting material in interiors is smaller • Solar wind is weaker farther out, or else their magnetospheres would be even smaller • we can not explain the magnetic field tilts of Uranus & Neptune. © 2005 Pearson Education Inc., publishing as Addison-Wesley The high energy particles come down the field lines and hit the atmosphere near the poles, causing the gases to glow. Just like on the Earth, this makes an “aurora” in a ring-like zone. Auroral Zones © 2005 Pearson Education Inc., publishing as Addison-Wesley The 4 “Jovian” Worlds • Major features : Massive: 14 - 300 x mass of Earth Gaseous: Hydrogen, Helium & Water Rocky Core (Si, O, Fe, Ni …) Rotating Fast: 10 hours (squashed shape) © 2005 Pearson Education Inc., publishing as Addison-Wesley