Jupiter

JupiterLargest and most massive planet in the solar systemContains almost ¾ of all planetary matter in the solar system.

Explored in detail by several space probes:

Pioneer 10, Pioneer 11, Voyager 1, Voyager 2, Galileo

Most striking features visible from Earth: Multi-

colored cloud belts

Visual image

Infrared false-color image

Exploration of Jupiter

Previous Missions

Pioneer 10 & 11Voyager 1 & 2

Latest Jupiter Mission

Galileo (1995 - 2003)

Galileo Probe

What did it tell us?

What did we expect?

Jupiter’s Rotation

Jupiter is the most rapidly rotating planet in the solar system

Rotation period slightly less than 10 hr.

Centrifugal forces stretch Jupiter into a markedly oblate shape.

Jupiter’s Atmosphere

Jupiter’s liquid hydrogen ocean has no surface:

Gradual transition from gaseous to liquid phases.

Only very thin atmosphere above cloud

layers;

transition to liquid hydrogen zone ~ 1000 km below

clouds.

Jupiter’s Cloud layers• Haze (at the top)• Ammonia• Ammonium Hydrosulfide• Water (lowest observed layer)

What did the Probe find?

At depth of 1 bar (Earth Sea level):

T = 130 K (-225 F), P=1 bar

Survived to a depth of 150 km:

T = 425 K (305 F), P=22 bars

Hotter and denser than expected

Ammonia and water layers were not detected

Wind velocities much greater (435 mph)

Chemically like Sun in terms of H, He, but a bit off in other elements

Jupiter’s AtmosphereThree layers of clouds:

1. Ammonia

(NH3) crystals

2. Ammonia hydrosulfide

(NH4SH)

3. Water crystals

Heating mostly from latent, internal heat

Observations of Jupiter from the Earth reveal clouds and atmospheric structures

Belts

Zones

The Cloud Belts of JupiterDark belts and bright zones.

Zones higher and cooler than belts; high-pressure regions of

rising gas.

The Cloud Belts on JupiterJust like on Earth, high-and low-pressure

zones are bounded by high-pressure winds.

Jupiter’s Cloud belt structure has remained unchanged since humans began mapping them.

Clouds, clouds, cloudsRotation rate is about 10 hours

Differential Rotation (different parts rotate at different rates)

Produces turbulence, and storms

© Calvin Hamilton

The Great Red Spot

8-year sequence of images of the Great Red Spot on Jupiter

Has been visible for over 400 years

Giant storm system similar to Hurricanes on Earth: Wind speeds of 430 km/h (= 270 miles/h)Changes appearance gradually over time

The Great Red Spot

A storm that has been going on for nearly 400 years

2-3 x size of the Earth

The History of Jupiter Formed from cold gas in the outer solar nebula, where ices were able to condense.

Rapid growth

Soon able to trap gas directly through gravity

Heavy materials sink to the center

In the interior, hydrogen becomes metallic (very good electrical conductor)

Rapid rotation → strong magnetic field

Rapid rotation and large size → belt-zone cloud pattern

Dust from meteorite impacts onto inner moons trapped to form ring

Jupiter’s Magnetic FieldMagnetic field at least 10 times stronger than Earth’s magnetic field.

Magnetosphere over 100 times larger than Earth’s magnetosphere

Aurorae on JupiterJust like on Earth, Jupiter’s magnetosphere produces aurorae concentrated in rings around the magnetic poles. ~ 1000 times more powerful than aurorae on Earth.

Particles producing the aurorae originate mostly from moon Io

Aurora requires a magnetic field

What’s Jupiter’s magnetic field like?

How is it produced?

Rock and Metal

Liquid MetallicHydrogen

Liquid Hydrogen

Molecular Hydrogen

Jupiter’s Ring System

Jupiter’s RingNot only Saturn, but all four gas giants have rings.

Jupiter’s ring: dark and reddish;

only discovered by Voyager 1

spacecraft.

Galileo spacecraft image of Jupiter’s ring, illuminated from behind

Composed of microscopic particles of

rocky material

Location: Inside Roche limit, where larger bodies (moons) would be destroyed by tidal forces.

Satellites of Jupiter

Currently 60+ known satellites - most

Most small asteroid-like, only a few km in size

4 largest satellites are the Galilean Satellites

Io, Europa, Ganymede, Callisto

The Galilean Satellites

Io - The Volcanic World

Io: Bursting EnergyMost active of all Galilean moons; no impact craters visible at all.

Over 100 active volcanoes!

Interior is mostly rock.

Activity powered by tidal interactions with Jupiter.

Surface features have changed since the Voyager spacecraft visited (1979) and the Galileo spacecraft’s observations (late 1990’s)

Continual volcanic eruptions

Why?

Io has the highest density

Io has the fewest craters - youngest surface

Io is closest to Jupiter

And on the other side are the other 3 large satellites

Io is a victim of a tug of war (tidal heating) due to Jupiter and the other moons!

Jupiter’s Influence on its MoonsPresence of Jupiter has at least

two effects on geology of its moons:

1. Tidal effects: possible source of heat for interior of Ganymede

2. Focusing of meteoroids, exposing nearby satellites to more impacts than those further out.

Interactions with Jupiter’s MagnetosphereIo’s volcanoes blow out sulfur-rich gases

→ tenuous atmosphere, but gases can not be retained by Io’s gravity

→ gases escape from Io and form an ion torus in Jupiter’s magnetosphere.

→ Aurorae on Jupiter are fueled by particles from Io

Europa - The Ice World

Europa: A Hidden Ocean

Close to Jupiter → should be hit by many meteoroid impacts; but few craters visible.

→ Active surface; impact craters rapidly erased.

The Surface of Europa

Cracked surface and high albedo (reflectivity) provide further evidence for geological activity.

Ice features that are slowly changing

Very few craters

Lower density than Io

Slightly older surface

The Interior of EuropaEuropa is too small to retain its internal heat → Heating mostly from tidal interaction with Jupiter.

Europa has a liquid water ocean ~ 15 km below the icy surface.

Ganymede - The Largest Moon

Ganymede: A Hidden PastLargest of the 4 Galilean moons. Rocky core

Ice-rich mantle Crust of ice

1/3 of surface old, dark, cratered; rest: bright, young, grooved terrain

Bright terrain probably formed through flooding when surface broke

Light and Dark Terrain indicates some resurfacing

Lower Density

More craters, Less resurfacing

Older surface than Europa

Callisto - The Cratered Moon

Callisto: The Ancient FaceTidally locked to Jupiter, like all of Jupiter’s moons.

Composition: mixture of ice and rocks

Dark surface, heavily pocked with craters.

No metallic core: Callisto never differentiated to form core and mantle.→ No magnetic field.

Layer of liquid water, ~ 10 km thick, ~ 100 km below surface, probably heated by radioactive decay.

Valhalla Impact Basin - rings extend out 1500 km

Lowest Density

Most craters

Very little resurfacing

Oldest surface