Lecture 20: Jupiter

"By Jove, I think she's got it!"
My Fair Lady

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Date: November 18, 1994
Reading Assignment: pp. 260-281

Description : overview of Jupiter and it's moons

Objectives

Be able to describe the composition of Jupiter's atmosphere.

Be able to describe the magnetosphere of Jupiter.

Be able to describe the differences between the inner and outer Galilean Moons.

Be able to discuss the basic characteristics of Jupiter, such as mass, rotation, composition, and orbital characteristics.

Understand that the moons of Jupiter probably did not all form in the same way.

Be able to describe the temperature of Jupiter and why this temperature is a bit unexpected.

Be able to explain differential rotation.

Lecture Outline

Slide # 1: Lecture 12- Jupiter

Slide # 2: Jupiter

orbit and rotation

composition and internal structure

surface features and history

atmosphere

magnetosphere

moons

Slide # 3: Planetary Structure

core

mantle

crust

hydrosphere

atmosphere

magnetosphere

Slide # 4: Jovian Planet Sizes Slide # 5: Planetary Orbits

outer solar system

Slide # 6: Jupiter- Revolution

semimajor axis = 5.20 AU

slightly elliptical orbit

orbital period = 11.9 Earth Years

Slide # 7: Moons

Mercury, Venus - none

Earth - 1

Mars - 2

Jupiter - 16

Saturn - 18

Uranus - 15

Neptune - 8

Pluto - 1

Slide # 8: Planetary Masses

Mercury = 1/20

Venus = 4/5

Earth = 1

Mars = 1/9

Jupiter = 318

Saturn = 95

Uranus = 15

Neptune = 17

Pluto = 0.002

Slide # 9: JupiterÕs Rotation

rotation is usually measured by observing surface features

Jupiter has no surface

Slide # 10: Measurements of JupiterÕs Rotation

observing cloud

Doppler measurements

magnetic fields

Slide # 11: JupiterÕs Rotation

9h 50m at the Equator

9h 56m near the poles

differential rotation

clouds are rotating at different speeds

Slide # 12: Differential Rotation

Jupiter is NOT a solid planet

Slide # 13: Magnetic Field Measurements

JupiterÕs core seems to be rotating every 9h 56m

detected by analysing radio signals

Slide # 14: JupiterÕs Rotation

fastest rotation of any planet in the solar system

causes Jupiter to have an equatorial bulge

Slide # 15: JupiterÕs Shape

oblateness of 0.065

Slide # 16: Atmospheric Composition of Jupiter

hydrogen (86.1%)

helium (13.8%)

traces of other gases (<1%)

methane

ammonia

water vapor

Slide # 17: Views of Jupiter

ground-based telescope

Slide # 18: Views of Jupiter

Voyager 1 Spacecraft

Slide # 19: Cloud Layers of Jupiter

structure of the atmosphere

Slide # 20: Why the Pretty Colors?

complex chemistry in the atmosphere

difficult to understand all the chemistry without more data

Slide # 21: Atmospheric Zones

bright zones

rising regions

dark belts

sinking regions

parts of the convection cycle

caused by circulation of the atmosphere

Slide # 22: Zones and Belts

side view

Slide # 23: The Red Spot

ancient hurricane on Jupiter

Slide # 24: Weather on Jupiter

the Great Red Spot

300 year old hurricane

25,000 km in diameter

many turbulent oval features

lightning detected

aurora detected

Slide # 25: Shoemaker- Levy 9

optical view of Jupiter

Slide # 26: Shoemaker- Levy 9

infrared view of Jupiter

Slide # 27: Shoemaker-Levy 9

donÕt let this happen to your planet

Slide # 28: Atmospheres

molecular speed and escape velocity

Slide # 29: Origin of the Atmospheres

primary atmosphere- Hydrogen and Helium

gases common in the solar system

nearly identical to SunÕs composition

too cold and too much gravity for any gases to escape

Slide # 30: Surface Heating of Planets

Most planets are warmed mainly by the SunÕs energy

sunlight strikes planetÕs surface and is absorbed

planet warms

planet radiates as a Black-Body

Slide # 31: Temperature of Jupiter

expected temperature should be 105K

measured temperature is 125K

20K difference in temperature

Slide # 32: Energy Radiated

StephanÕs Law

energy proportional to temperature to fourth power

(125/105)4 = (actual energy / solar energy)4

Jupiter radiates twice as much energy as it receives from the Sun

Slide # 33: JupiterÕs Heat

NOT the Greenhouse effect

More energy is leaving Jupiter than arrives

Jupiter has an internal heat source

Slide # 34: JupiterÕs Heat

energy cannot be nuclear fusion or fission

not enough compression for fusion

not enough radioactive elements for fission

must be energy from the gravitational from the planetÕs formation

Slide # 35: Internal Structure

no seismic information is possible

we must rely on computer models

some tests possible through observations

Slide # 36: Internal Structure

big ball of mostly hydrogen

Slide # 37: Exploration of Jupiter

Pioneer 10 (December 1973)

Pioneer 11 (December 1974)

Voyager 1 (March 1977)

Voyager 2 (July 1977)

Slide # 38: Magnetic Fields

two conditions needed to form magnetic fields

liquid metal core

rapid rotation

Jupiter has rapid rotation and a large metallic hydrogen core

Slide # 39: Magnetic Field from Jupiter

Jupiter has a GIANT magnetosphere

Slide # 40: Magnetosphere

the magnetosphere extends over 5 AUÕs

20,000 times stronger than EarthÕs magnetic field

radiation belts thousands of times stronger than EarthÕs

Slide # 41: Moons of Jupiter

at least 16 moons

four major groups of moons

inner satellites

Galilean satellites

prograde outer satellites

retrograde outer satellites

Slide # 42: Inner Moons

seem to be similar to large asteroids

probably big rocks

Slide # 43: Inner Moons

orbital sizes 1.79 to 3.11 planetary radii

diameters 20 to 200 km

low reflectivity

Albedo 0.05

circular orbits

Example: Amalthea

Slide # 44: Amalthea

potatos in space

Slide # 45: Galilean Moons

discovered by Galileo

orbital sizes 5.91 to 26.4 planetary radii

diameters 3140 to 5260 km

high reflectivity

Albedo 0.2 to 0.6

circular orbits

Io, Europa, Ganymede, Callistro

Slide # 46: Galilean Moons

Io and Europa

rocky composition- density 3.6 and 3.0 gm/cm3

inner Galilean moons

Callisto and Ganymede

lighter materials- lots of icy materials

lower density - 1.9 gm/cm3

outer Galilean moons

All these moons have

circular orbits

near the equatorial plain of Jupiter

Slide # 47: Prograde Moons

orbital sizes 155 to 164 planetary radii

diameters 239 to 260 km

low reflectivity

Albedo 0.03 to 0.05

eccentric (elliptical) orbits

Example: Leda

Slide # 48: Retrograde Moons

orbital sizes 297 to 332 planetary radii

diameters 30 to 70 km (?)

reflectivity- unknown

orbits eccentric and RETROGRADE

Example: Pasiphae

Slide # 49: Outer MoonÕs Origin

retrograde outer moons were almost certainly captured

probably originally ONE bigger moon which broke apart

prograde outer moons were probably captured

probably orginally ONE bigger moon which broke apart

Slide # 50: Geology of the Big Moons

the Galilean moons are a great chance to look at other ÒTerrestrial PlanetsÓ

Slide # 51: Io

moon of pizza

Slide # 52: Io

ACTIVE volcanos

eruptions detected by Voyager 1 and 2

heating and volcanos caused by tidal forces from Jupiter

Slide # 53: Volcanics on Io

Voyager detected volcanic plume

Slide # 54: Volcanos on Io

tidal forces from Jupiter squeeze Io

Slide # 55: Europa

few craters

frozen WATER ICE

many crossed lines

white color

possible geyser eruptions

possible water ocean under the ice

Slide # 56: Europa

broken cue-ball in space

Slide # 57: Ganymede

similar to the structure of EarthÕs Moon

water on Ganymede replaces lava on the Moon

frozen maria cover much of the landscape

Grooved terrain and ridges may come from ancient plate tectonics

Slide # 58: Ganymede

icy craters and grooves

Slide # 59: Callisto

similar to Ganymede

more craters and fewer faults

evidence of a big impact in the Valhalla basin

no evidence of plate tectonic activity

froze before plates could form

Slide # 60: Callisto

icy craters and a big impact

Slide # 61: Galilean Moons

moons and more moons

Slide # 62: JupiterÕs Ring

Jupiter has a faint ring

similar to the ring of Saturn, but much much less spectular

Slide # 63: Views of Jupiter

ring around the planet

Slide # 64: Jupiter

orbit and rotation

composition and internal structure

surface features and history

atmosphere

magnetosphere

moons