Class 8: Jupiter, Saturn,Uranus, Neptune, Pluto

Today’s topics: Jupiter & Saturn

• Jupiter: Internal structure, magnetic field

atmosphere, moons

• Saturn: Exploration, internal structure,

rings

• The other guys: Uranus, Neptune, Pluto

Class Updates

• Reading: 23.2, 23.4-23.6

• Midterm 2: April 18th

Class 8: Jupiter, Saturn,Uranus, Neptune, Pluto

mostly H2

• Size (radius) 6378 km 11x Earth

Jupiter: A Global Perspective

Differences Earth Jupiter

• Mass 6x1024 kg 317x Earth

• Density 5.5 g/cm3 1/4 of Earth

• Atmosphere 78% N2 21% O2 86% H2 14% He

• Surface temperature 20°C -120°C

• Plate tectonics yes no

• Tectonism, volcanism yes no

• Liquid water yes no

• Rotation 1 day 2/5 of Earth• Orbit 1 yr 11.9 yrs

• Pioneer 10 & 11 fly-bys 1974/75US

Exploration of Jupiter

CassiniGalileoVoyager 2Pioneer 10

• Voyager 1 & 2 fly-bys 1979 US

• Galileo fly-by 1995-2003 USprobe

• Cassini fly-by 2004 US/Europe

Jupiter’s Internal Structure

~12,000 km

60,000 km

(1)

(2)

(3)core

30,000 °C

Electron (-1)

Nucleus: Proton (+1) Neutron (0)

Molecular & Metallic Hydrogen

Magnetic Field Generation?

rocky core liquid metallic hydrogen molecular

hydrogen

EarthJupiter

Jupiter’s Magnetic Field

artist’s rendition

Jupiter’s Atmosphere

Voyager 2

Voyager 1

warmcool

The Great Red Spot

2006: New “Junior” Red Spot

Jupiter’s Rings

Voyager 1 (pseudo color)

Halo Ring (inner-most)

Jupiter & moons (backyard telescope)

1,000,000 miles

Jupiter’sMoons

Jupiter’s Moons: 65 & counting……..

Saturn

mostly H2

Saturn: A Global Perspective

• Size (radius) 6378 km 9x Earth

Differences Earth Saturn

• Mass 6x1024 kg 95x Earth

• Density 5.5 g/cm3 0.70 g/cm3

• Rotation 1 day 1/2 of Earth

• Atmosphere 78%N2 21%O2 90%H2 10%He

• Surface temperature 20°C -180°C

• Plate tectonics yes no

• Tectonism, volcanism yes no

• Liquid water yes no

Exploration of Saturn

CassiniVoyager 2

• Voyager 1 & 2 fly-bys 1979 US

• Cassini-Huygens orbiter (Saturn) 2004 US/Europe probe (Titan) 2005

Huygens Probe

Cassini Observations

Saturn’s Internal Structure (I)

(1)

• Layer 1: molecular hydrogen

30,000 km

• Layer 3: water, methane, ammonia

(3)

(2)

• Layer 2: metallic hydrogen

• Core: heavy-elements(?)

core

Saturn’s Internal Structure (II)

molecular H

core

Saturn: 0.70 g/cm3

metallic H

• less dense than Jupiter

Jupiter: 1.3Water: 1.0

Saturn’s Rings

Saturn’s Rings Characteristics

Mimas

Enceladus

TitanEpimetheus

Rhea

Saturn’s Moons

Dione

Tethys

Iapetus

Uranus, Neptune, and Pluto

Solar System Distances

*Planets not to scale Distances not to scale

Uranus: A Global Perspective

Differences EarthUranus• Size (radius) 6378 km 4x

Earth• Mass 6x1024 kg 145 Earth

• Density 5.5 g/cm3 1.3 g/cm3

(methane)• Atmosphere 78%N2 21%O2 84%H 14%He 2%CH4

• Surface temperature 20°C -200°C

• Rotation 1 day -17.9 hours

• Orbit 365 days 84.01 years

• Satellites 1 27

Exploring Uranus

Herschel

Uranus moons

Voyager 2Hubble Space Telescope

Uranus’s Interior

(1)

(2)

core

METHANEMETHANE

Axis of Rotation

98 °

Uranus

23.5°

Earth

Atmosphere & Magnetic Fieldultraviolet

visible

rotationaxis

magneticaxis

58°

The Rings of

Uranus

dust bands

Ariel

Umbriel

Oberon (2nd largest) Titania

(largest)

Miranda

Puck

Total: 27

The Moons of Uranus

r ≈ 789 km

Neptune: A Global Perspective

Differences EarthNeptune• Size (radius) 6378 km 3.9x

Earth• Mass 6x1024 kg 171 Earth

• Density 5.5 g/cm3 1.6 g/cm3

(methane)• Atmosphere 78%N2 21%O2 84%H 14%He 2%CH4

• Surface temperature 20°C -210°C

• Rotation 1 day 16 hours

• Orbit 365 days 165 years

• Satellites 1 11

Exploring Neptune

Adams

Le Verrier

Galle

Voyager 2

Neptune’s Interior

H, He, CH4

H2O, CH4, NH3

(1)

(2)

core

Neptune’s Atmosphere & Clouds

Scooter

Neptune clouds

The Great Dark Spot

Voyager 2

GDS changesVoyager 2

Voyager 2

Neptune’s Rings & Moons

faint rings

Triton

A Parting Look

Pluto: A Global Perspective

Similarities EarthPluto• Moon 1 - Moon 1 - Charon

• Size (radius) 6378 km 0.2x Earth

Differences

• Mass 6x1024 kg 0.002x Earth

• Density 5.5 g/cm3 0.4x Earth

• Atmosphere 78% N2 21% O2 probably N2, thin

• Surface temperature 20°C -220°C

• Rotation 1 day 6.4 days

• Orbit 365 days 248 years

Exploring Pluto

Tombaugh, Lowell Observatory

Charon

Photo 1 Photo 2

planetary symbol

Pluto’s Elliptical Orbit

Pluto: Is it a planet?

Real Planets & Dwarf Planets

ErisPlutoCeres

Pluto’s Size & Interior

core

Pluto - Charon System

112°

Pluto and Charon from Hubble

Bright/dark regions: differences in methane/nitrogen frost cover

New Horizons Mission