Jupiter - Astronomy

Giant Planets Neptune Uranus Saturn

Jupiter

Lecture 15: The Planets

Homework Read Chapter 11: “Jovian Planet Systems”

Homework: Mastering Astronomy due Friday at 6pm.

Midterm #2 • Tuesday, Nov. 4: One week from today. • Covers Chapters: 9, 10, 11, 14 • 30 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.

Terrestrial (Rocky)

Outer 4 Planets: Gas Giants

The Solar System

Spacecraft Reconnaissance 1980’s: Voyager 1 & 2 Camera and Spectrometer

Measures spectral lines: Chemical composition

Visited all 4 giant planets

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 1995-2003

•Launched from Space Shuttle 1989

Galileo Spacecraft Arrived: 1995

2003: Dropped into Jupiter’s Atmosphere: Measure Chemical Composition:

The 4 “Giant Planets” “Jovian Planets” • No solid surfaces !!!

Jupiter H & He (most common atoms in universe)

Much higher mass & radius than Earth, Venus, Mars.

Saturn H & He

Uranus

Neptune

H & He,

H & He,

H2O

H2O

(Textbook: “hydrogen compounds” = water: H2O methane: CH4 ammonia: NH3

All four Gas Giants have rocky cores (silicates+iron) of 10-20 Earth masses.

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

Fractional composition in mass %. Jupiter

H

Sun

Jupiter

Sun

0.742

0.736

Ne

He

0.231(4)

0.249

P

< 0.00007

0.00001

C

0.009(2)

0.0029

S

0.00091(6)

0.00050

N

< 0.012

0.00085

Ar

< 0.00015

0.00007

O

< 0.0035

0.0057

“Z”

0.027

0.015

0.00023(3)

0.0018

Jupiter – King of the Planets Mass = 0.001 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.

10.5 RE 11.2 RE

Flattened Spheroid

Saturn Mass = 95 Earths (only 30% of Jupiter) Radius = 9.4 Earths Density = 0.7 gram/cm3 (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 Phases of Hydrogen

Density

Computer Simulation: Molecular and Metallic hydrogen

Molecular hydrogen •Electrons bound to molecules

Metallic hydrogen •Electrons free to move

“Phases” of Hydrogen: The Interiors of Jupiter & Saturn Phases of Hydrogen

Density

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

Interior of Jupiter A New Probe: “Juno”

Surfaces of the Giant Planets

Jupiter

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

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

Cassini (2000)

Jupiter’s Atmosphere

Jupiter’s Atmosphere

Convection on Jupiter:

Bands of Jupiter What Causes them? •Warm air rises •Coriolis force diverts path sideways Coriolis force is due to rotation of planet

•Jupiter rotates fast: Period = 10 hours

Winds of Jupiter’s Bands

Red Spot

in Southern Hemisphere

Great Red Spot

A Hurricane that has lasted 300 years

Giant red spot

Giant red spot in motion

Red Oval

Red Oval in motion

Cyclones and Anticyclones on Jupiter

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

Cyclonic Motions

Southern Hemisphere

Northern Hemisphere

Coriolis effect: Motion from High Pressure area

Comparison of Cyclones and Anti-Cyclones Cyclones:

Anti-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,

High-pressure weather phenomena, Winds blow outwards, Example: Jupiter’s red spot Rotate clockwise on Northern hemisphere, Rotate counter-clockwise on Southern hemisphere,

What is this? (A) (B) (C) (D)

Anti-cyclone on northern HS Cyclone on the northern HS Anti-cyclone on the southern HS 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 Radius = 4.0 Earths Density = 1.3 gram/cm3 = 1.3 x water Distance: 19.2 AU

Visible Light

Featureless in visible light, because clouds are below haze layer of methane (colder than Saturn).

Orbital Period: 84 years;

Rotation period: 17.2 hours.

Infrared Light (Thermal Emission)

Uranus – Yes Plenty of Clouds 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! Gaseous envelope of H, He, and some CH4 Liquid mixture of H2O, CH4, NH3 ices Rocky core (silicates+iron)

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.

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 !

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 Track acceleration of satellites accurately

—> Exerts Point-like Gravitational Force —> Density profile throughout interior

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.

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.

Thursday’s Lecture:

Moons orbiting the Giant Planets

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? Jupiter’s Moon: Io

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

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 But Jupiter’s mass is only (C) 100 Earth masses 318 Earth masses. What does (D) 1000 Earth masses this tell us?

Neptune’s Storms

scooter

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) (high altitude) • ammonium hydrosulfide (NH4SH) • water (H2O)

They condense at different temperatures, so their clouds form at different altitudes.

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

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.

Jupiter

Uranus

Magnetic Fields

Neptune

Saturn

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

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