Giant Planets Saturn Uranus Neptune Jupiter Lecture 15: The Planets Lecture 15: The Planets

Homework Read Chapter 11: “Jovian Planet Systems” “Jovian Planet Systems” Homework: Mastering Astronomy due Friday at 6pm. due Friday at 6pm.

Midterm #2 Tuesday, Nov. 4: One week from today. Covers Chapters: 9, 10, 11, Multiple choice questions Study Approach: - Review Lectures (PDFs, webcast.berkeley.edu) - For each topic, ask, “Do I really understand this?” If not, read the book, or go to Office Hours or Disc. Session. - Review all homework problems - Go to Discussion Sections or Office Hours for review and help.

© 2005 Pearson Education Inc., publishing as Addison- Wesley The Solar System Terrestrial (Rocky) Outer 4 Planets: Gas Giants

Spacecraft Reconnaissance 1980’s: Voyager 1 & 2 Camera and Spectrometer Visited all 4 giant planets Measures spectral lines: Chemical composition

Voyager Spacecraft: Movie of Jupiter

Approach of Voyager Spacecraft In Rotating Frame of Reference This is the Voyager 'Blue Movie' (so named because it was built from blue filter images). It records Voyager 1's approach during a period of 60 Jupiter days. Notice the difference in speed and direction of the various zones of the atmosphere.

Voyager Spacecraft: Movie of Jupiter: In Rotating Frame of Reference

Galileo Spacecraft Visited Jupiter Launched from Space Shuttle 1989

Galileo Spacecraft Arrived: : Dropped into Jupiter’s Atmosphere: Measure Chemical Composition:

The 4 “Giant Planets” “Jovian Planets” Much higher mass & radius than Earth, Venus, Mars. No solid surfaces !!! H & He (most common atoms in universe) (Textbook: “hydrogen compounds” = water: H2O methane: CH4 ammonia: NH3 Jupiter Saturn Uranus Neptune All four Gas Giants have rocky cores (silicates+iron) of Earth masses. All four Gas Giants have rocky cores (silicates+iron) of Earth masses. H & He H & He, H 2 O H & He, H 2 O

Comparison of Sun’s and Jupiter’s composition (as measured by the Galileo Probe) Jupiter Sun Jupiter Sun No solid surface and consists mostly of H & He. Distinct interior layers, defined by increasing density inward. Fractional composition in mass %.

© 2005 Pearson Education Inc., publishing as Addison- Wesley Jupiter – King of the Planets Mass = solar (318 Earth masses), Radius = 10.5 … 11.2 Earth radii, Density = 1.3 g/cc (1.3 x water) Distance: 5.2AU Orbital Period: 11.8 years Rotation period: 9:55 hours. Flattened Spheroid 11.2 R E 10.5 R E

© 2005 Pearson Education Inc., publishing as Addison- WesleySaturn Mass = 95 Earths (only 30% of Jupiter) Radius = 9.4 Earths Density = 0.7 gram/cm 3 (floats) Distance: 9.5 AU Orbital Period: 29.4 years Rotation period: 10.6 hours. Rings: Composed of billions of icy rocks and icy dust particles (water ice and silicates).

Interior of Jupiter and Saturn

“Phases” of Hydrogen: The Interiors of Jupiter & Saturn Density Temperature (K) Phases of Hydrogen

Computer Simulation: Molecular and Metallic hydrogen Molecular hydrogen Metallic hydrogen Electrons free to move Electrons bound to molecules

“Phases” of Hydrogen: The Interiors of Jupiter & Saturn Density Temperature (K) Phases of Hydrogen

A New Probe of Jupiter: “Juno” Launch August 5, 2011

Interior of Jupiter A New Probe: “Juno”

Surfaces of the Giant Planets

© 2005 Pearson Education Inc., publishing as Addison- Wesley

Jupiter

Jupiter’s Atmospheric Properties Rotation Period = 9 hours 55 minutes (based on Jupiter’s magnetic field) Cassini (2000) Rotation Period = 9 hours 55 minutes (based on Jupiter’s magnetic field) Cassini (2000)

Jupiter’s Atmosphere Cassini (2000)

Jupiter’s Atmosphere Cassini (2000)

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 Bands of Jupiter What Causes them?

Red Spot in Southern Hemisphere Winds of Jupiter’s Bands

© 2005 Pearson Education Inc., publishing as Addison- Wesley

A Hurricane that has lasted 300 years Great Red Spot

Giant red spot in motion Giant red spot

Red Oval in motion Red Oval

Cyclones and Anticyclones on Jupiter

Red Spot Jr. spot formed from three white ovals and later turned red.

Cyclonic Motions Coriolis effect: Motion from High Pressure area NorthernHemisphere SouthernHemisphere

Cyclones: Low pressure weather phenomena, Winds blow inwards, Typical storm systems on Earth Rotate counter-clockwise on Northern hemisphere, Rotate on clockwise on Southern hemisphere, Anti-Cyclones: High-pressure weather phenomena, Winds blow outwards, Example: Jupiter’s red spot Rotate clockwise on Northern hemisphere, Rotate counter-clockwise on Southern hemisphere, Comparison of Cyclones and Anti-Cyclones What is this? (A)Anti-cyclone on northern HS (B)Cyclone on the northern HS (C)Anti-cyclone on the southern HS (D)Cyclone on the southern HS

Jovian Storms Red Spot: A High Pressure Storm Analogous to hurricanes (low pressure systems, material flows in), but they rotate in the opposite direction because they high pressure systems where material flow out Jupiter the Great Red Spot we are not sure why it is red Neptune the Great Dark Spot Planet Rotation

Uranus – Haze but any Clouds? Mass = 14.5 Earths Orbital Period: 84 years; Radius = 4.0 Earths Density = 1.3 gram/cm 3 = 1.3 x water Distance: 19.2 AU Rotation period: 17.2 hours. Visible LightInfrared Light (Thermal Emission) Featureless in visible light, because clouds are below haze layer of methane (colder than Saturn).

Visible Light Featureless in visible light, because clouds are below haze layer of methane (colder than Saturn). Uranus – Yes Plenty of Clouds

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.

Uranus & Neptune Giants of H, He, and Water! Rocky core (silicates+iron) Liquid mixture of H 2 O, CH 4, NH 3 ices Gaseous envelope of H, He, and some CH 4

© 2005 Pearson Education Inc., publishing as Addison- Wesley Hydrostatic Equilibrium: Pressure balance “Hydrostatic equilibrium” governs the structure of all planets. The inside has higher pressure and density because of the weight of the overlying material. Pressure at any depth = gravitational weight of column above

Inside Giant Planets Saturn emits almost twice as much energy as it absorbs from the Sun. Neither Cooling nor Radioactivity can account for it Saturn must a different “secret” heat source Jupiter has 3x more mass than Saturn, but is only slightly larger in radius! the added weight of H & He compresses the gases below to a higher density like stacking pillows If Jupiter had 10x its mass, it would have same radius ! Add even more mass, and Jupiter would get smaller ! Jupiter is 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: More Rock & Water !

Rotation flattens shape—> Less pull on satellite at poles Higher density toward center —> Exerts Point-like Gravitational Force Track acceleration of satellites accurately Density profile throughout interior —> Density profile throughout interior Determining the Density inside a Rotating Planet Use Motion of Orbiting Satellites

Interactive Quiz How would you land on Jupiter? (A)With parachutes (B) With thrust rockets (C) With pontoons like a seaplane (D) You cannot land on Jupiter. How would you land on Jupiter? (A)With parachutes (B) With thrust rockets (C) With pontoons like a seaplane (D) You cannot land on Jupiter.

Interactive Quiz How would you land on Jupiter? (A)With parachutes (B) With thrust rockets (C) With pontoons like a seaplane (D) You cannot land on Jupiter. How would you land on Jupiter? (A)With parachutes (B) With thrust rockets (C) With pontoons like a seaplane (D) You cannot land on Jupiter.

Jupiter’s Moon: Io A volcanic explosion can be seen silhouetted against dark space over Io's brilliant limb. Io more volcanically active than Earth. How many Jovian moons are there? A volcanic explosion can be seen silhouetted against dark space over Io's brilliant limb. Io more volcanically active than Earth. How many Jovian moons are there? Thursday’s Lecture: Moons orbiting the Giant Planets

© 2005 Pearson Education Inc., publishing as Addison- Wesley Jupiter – King of the Planets Radius = 10.5 … 11.2 Earth radii Suppose you make a bigger Earth that has a radius 10 times larger, but rocky! Assume the density would be the same as Earth (5.5 g/cc). What would its mass be? (A)The same, one Earth mass (B) 10 Earth masses (C) 100 Earth masses (D) 1000 Earth masses Suppose you make a bigger Earth that has a radius 10 times larger, but rocky! Assume the density would be the same as Earth (5.5 g/cc). What would its mass be? (A)The same, one Earth mass (B) 10 Earth masses (C) 100 Earth masses (D) 1000 Earth masses

© 2005 Pearson Education Inc., publishing as Addison- Wesley Jupiter – King of the Planets Radius = 10.5 … 11.2 Earth radii Make a bigger Earth that has a radius 10 times larger. Assume the density would be the same, what would its mass be? (A)The same, one Earth mass (B) 10 Earth masses (C) 100 Earth masses (D) 1000 Earth masses Make a bigger Earth that has a radius 10 times larger. Assume the density would be the same, what would its mass be? (A)The same, one Earth mass (B) 10 Earth masses (C) 100 Earth masses (D) 1000 Earth masses But Jupiter’s mass is only 318 Earth masses. What does this tell us?

© 2005 Pearson Education Inc., publishing as Addison- Wesley scooter Neptune’s Storms

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 (NH 3 ) (high altitude) ammonium hydrosulfide (NH 4 SH) water (H 2 O) They condense at different temperatures, so their clouds form at different altitudes. Altitude above clouds tops (km) Temperature (°C)

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

Aurora Borealis near Jupiter’s North Pole

© 2005 Pearson Education Inc., publishing as Addison- Wesley Auroral Zones The high energy particles come down the magnetic 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.

Magnetic Fields Jupiter Saturn UranusNeptune

Jupiter's Magnetosphere 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.

© 2005 Pearson Education Inc., publishing as Addison- Wesley Jupiter’s Magnetosphere – Bigger than the Sun Solar Wind protons & electrons

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.

Quiz If Jupiter formed in a protoplanetary disk that had twice as much dust in it: (A)Would have a bigger core (B) Might have more hydrogen (C)Might have more metallic hydrogen (D)All of the above

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 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