12a. Jupiter• Jupiter data• Jupiter seen from the Earth• Jupiter rotation & structure• Jupiter clouds• Jupiter atmospheric motions• Jupiter rocky core• Jupiter magnetic field

Jupiter Data (Table 12-1)

Jupiter Data: Numbers• Diameter: 142,800.km 11.19 Earth⋅• Mass: 1.9 10⋅ 27 kg 317.8 Earth⋅• Density: 1.3 water⋅ 0.24 Earth⋅• Orbit: 7.8 10⋅ 8 km 5.20 AU• Day: 9h.50m 30s 0.41 Earth⋅• Year: 11.86 years 11.86 Earth⋅

Jupiter Data: Special Features• Jupiter is the closest Jovian planet to the Sun• Jupiter is the largest Jovian planet

– Jupiter is ~2.5 . mass of all other planets combined• Jupiter has no solid surface• Jupiter has a colorful & dynamic atmosphere

– Great Red Spot, belts & zones…• Jupiter’s interior consists of three layers…

– Atmosphere: Liquid molecular hydrogen– Mantle: Liquid metallic hydrogen– Core: “Metal” & “rock”

• Jupiter has 4 large & 63 small known moons– Io is the most volcanically active body known

Jupiter As Seen From Earth• The first telescopic observer of Jupiter

– Galileo Galilei

1610• Immediately noticed the four largest moons of Jupiter• Recognized the similarity between them and the planets

• More recent telescopic observers– Robert Hooke

1664• Noticed the Great Red Spot in the southern hemisphere• It has persisted in some form until now

– Cassini

1690• Cloud bands drawn out by Jupiter’s very fast axial rotation• Used these to measure 9h 50m 28s equatorial Jovian day• Discovered Jupiter’s differential axial rotation

Rotation– Jupiter rotates fastest at its equator than at its poles

Jupiter is Made of Low-Mass Gases• Jupiter is mostly hydrogen & helium

– The numbers• By mass ~ 71% H2 ~ 24% He ~ 5% others

• By atoms ~ 91% H2 ~ 8% He ~ 1% others

– The evidence• Detected spectra of CH4 (methane) & NH3 (ammonia)

• Cold H2 & He are extremely difficult to detect– UV spectra detected in 1960

• Jupiter does have a rocky & metallic core– May have been the “seed” for the rest of Jupiter

Cloud Details in Spacecraft Images• Pioneer 10 & Pioneer 11 fly-bys 1973 & 1974

– First close-up images of Jupiter– Spectacular images of Galilean moons, esp. Io

• Voyager 1 & Voyager 2 fly-bys 1979– Spectacular close-ups of Jovian storm systems– Additional details of most Jovian moons

• Galileo atmospheric probe & orbiter 1995– Probe entered clear area in Jupiter’s clouds– Severely crippled yet operated until 21 Sep. 2003

• Cassini 2000– The primary mission is to Saturn– Imaged Jupiter during gravity-assist [slingshot] fly-by

• Simultaneous observations by Galileo

Patterns In Jupiter’s Clouds

Jupiter Seen From Far & Near

Earth-based telescope Voyager 1 spacecraft

Five Historic Views of Jupiter

Jupiter’s Great Red Spot• Solar System champ

– Longest lasting storm systemSince 1664

– Largest storm system~ 25,000 mi

• Basic characteristics– Imbedded in Jupiter’s southern hemisphere– Much higher than surrounding clouds– Circulates counterclockwise

• Characteristic of a high pressure system• Similar to high pressure systems in Earth’s atmosphere

– Size varies considerably• From ~ 1 to ~3 times Earth’s diameter

– Color varies considerably• From deep red to light pink

Voyager 2: The Great Red Spot

Jupiter & Ganymede: Family Portrait

Three Factors Affect Cloud Motions• Insolation Incoming solar radiation

– Jupiter’s orbit is ~ 5.2 AU from the Sun• ~ 3.7% as much energy per m2 as Earth

– Jupiter’s albedo is 0.44 compared to Earth’s 0.39• Effectively reduces solar energy to ~ 3.3% of Earth

– Sunlight is absorbed by Jupiter’s atmosphere• Jupiter’s internal heat

– Jupiter emits ~ 2x as much energy as from sunlight• Old heat from Jupiter’s formation• New heat from helium condensation

• Differential axial rotation– Multiple convection cells in Jupiter’s atmosphere– Drawn out into bands parallel to Jupiter’s equator

• Adjacent bands move in opposite directionsZonal winds

Spectroscopy of Jupiter’s Atmosphere• Three primary cloud layers

– Upper layer

~ 20 km below Tmin• Ammonia (NH3) ice crystals

– Middle layer

~ 40 km below Tmin• Ammonium hydrosulfide (NH4SH) ice crystals

– Lower layer

~ 60 km below Tmin• Water (H2O) ice crystals

• Major cloud features– Belts & zones

• Belts are bands of falling air Relatively low & warm

• Zones are bands of rising air Relatively high & cool

– Brown & white ovals• White ovals lie relatively high in Jupiter’s atmosphere

– Smaller versions of the Great Red Spot• Brown ovals lie relatively low in Jupiter’s atmosphere

Jupiter’s Upper Atmosphere Structure

Jupiter’s (Low) Belts & (High) Zones

Jupiter’s Distinctive Cloud Colors• Mostly “Earth tones”

– Yellow, brown, pink, red…– Colors vary over time & space

• Source of colors– All three cloud layer chemicals are white if pure

• Spectroscopy reveals no substantial impurities– Jupiter’s moon Io is extremely active volcanically

• Io has abundant sulfur compounds• Io has the same colors as Jupiter’s clouds• Io spews matter into space near Jupiter• Jupiter’s cloud colors may come from Io’s eruptions

Jupiter’s Deep Atmosphere: S-L 9• Comet Shoemaker-Levy 9 16-22 July 1994

– 23 visible fragments entered Jupiter’s atmosphere• All less than ~ 1 km in diameter• Entry speed of ~ 60 km sec⋅ –1

~ 130,000 mph– Satellites orbit Earth at ~ 8 km sec⋅ –1

• Largest fragment energy equivalent of 6 10⋅ 8 megatons

– 10,000°C fireballs rose 3,000 km above the clouds• Hopes for eruptions of deep atmospheric layers• Confounded by uncertainties about comet’s composition

S-L9: The String of Pearls Comet

Comet Shoemaker-Levy 9 Hits Jupiter

Jupiter’s Deep Atmosphere: Galileo• Galileo atmospheric probe 7 December 1995• Only spacecraft to enter Jupiter’s atmosphere

– Entry speed of ~ 49 km . sec–1

~ 106,000 mph– Decelerated to ~ 40 km . hr–1 in 3 min.

~ 25 mph– Descended by parachute for ~ 1 hour– Reached ~ – 200 km & + 24 x Earth’s air pressure

Jupiter’s Atmosphere Findings• Relatively rare but extremely powerful lightning• Nearly constant winds of ~ 650 km hr⋅ –1

– Much faster than solar-driven high altitude winds– This wind energy must come from Jupiter’s interior

• Cloud layer measurements– Galileo Probe’s bad luck Entered a clear spot⇒– Traces of NH3 & NH4SH clouds but no H2O clouds

• Atmospheric gases– Virtually identical to the Sun– Only ½ expected amount of atmospheric H2O vapor

The Galileo Probe Timeline

Probe video

Oblate Shape Means a Rocky Core• Distinctly larger equatorial than polar diameter

– ~ 6.5 % difference for Jupiter– ~ 0.34% difference for Earth

• Axial rotation spins equatorial material away– Centrifugal effect

• Planetary core mass modifies centrifugal effect– Metallic & rocky inner core

• Estimated to be ~ 2.6% of Jupiter’s mass• Only ~ 8 x Earth’s mass yet ~ 86% Earth’s diameter

– Liquid “ices” outer core• Primarily water (H2O), methane (CH4) & ammonia (NH3)• Estimated to be ~ 3,000 km thick

Jupiter’s Four-Layer Internal Structure

Jupiter's Interior

Metallic Hydrogen & Magnetosphere• Radio observations of Jupiter 1950’s

– Evidence of electric currents– Different types of radio emissions

• Thermal emissions

Blackbody radiation• Non-thermal emissions

– Wavelengths of a few meters

Decametric radiation– Wavelengths of a few tenths of a meter

Decimetric radiation• Jupiter’s magnetic field is ~ 14 x Earth’s magnetic field

• Possible causes– H2 is a liquid metal above 1.4 . 106 atmospheres

• Pressure is reached ~ 7,000 km below Jupiter’s clouds• The “gas giant” Jupiter is mostly liquid metallic hydrogen

Jupiter’s Immense Magnetosphere• Spacecraft measurements

– Pioneer & Voyager• Magnetosphere is ~ 3.0 . 107 km in diameter

– ~ 210 times Jupiter’s diameter as seen from Earth

– ~ 2.5 times the Moon’s diameter as seen from Earth

– ~ 6.3 times the Moon’s area as seen from Earth

• Magnetosphere extends beyond the orbit of Saturn– Jupiter’s magnetotail is ~ 6 AU long

• Emissions variations repeat every 9h 55m 28s– Assumed to be the core axial rotation rate of Jupiter

– Galileo• Suffered extensive radiation damage orbiting Jupiter

• Basic characteristics– Jupiter’s magnetosphere is filled with plasma– Solar wind gusts alter Jupiter’s magnetosphere

• Magnetosphere’s size varies by a factor of 2

Jupiter’s MagnetosphereA schematic

view

A radio view

Juno: Jupiter’s Newest Spacecraft• Basic details

– Launched 5 August 2011– Six-year planned mission

• 5 years from Earth to Jupiter Arrives 5 July 2016

• 1 year science mission• Science objectives

– Determine O2 abundance in Jupiter’s atmosphere– Better estimate of Jupiter’s core mass– Precisely map Jupiter’s interior mass distribution– Precisely map Jupiter’s magnetic field– Map variations in atmospheric properties– Jupiter’s polar magnetosphere & aurorae– Measure general relativistic orbital frame-dragging

Juno’s Scientific Instruments• Microwave radiometer• Jovian Infrared Auroral Mapper• Magnetometer• Gravity Science• Jovian Auroral Distribution Experiment• Jovian Energetic Particle Detector Instrument• Radio and Plasma Wave Sensor• Ultraviolet Imaging Spectrograph• JunoCam

http://upload.wikimedia.org/wikipedia/commons/b/ba/Juno%27s_interplanetary_trajectory.jpg

Juno’s Route to Jupiter

The Juno Spacecraft at Jupiter

http://upload.wikimedia.org/wikipedia/commons/b/b3/Juno_Mission_to_Jupiter_%282010_Artist%27s_Concept%29.jpg

The Juno Spacecraft 33 Orbits

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Juno’s Mission at Jupiter• Polar orbit

– Highly elliptical• Spend minimum time in Jupiter’s radiation belts• Planned 33 orbits• Juno de-orbited to crash into Jupiter

– Possibility of an extended mission• Mainly an issue of fuel for orientation thrusters

• Jupiter data– ~ 11.2 times Earth’s diameter– ~ 318 times Earth’s mass

• ~ 2.5 times the mass of all planets• Jupiter as seen from Earth

– Distinctly oblate shape– Distinctive cloud bands & storms– Four extremely obvious moons

• Distinctive features– Axial rotation period of ~ 10 hours– Solar System’s most colorful clouds– Composed mostly of H & He

• Almost same composition as the Sun• Jupiter’s cloud details

– Prominent cloud belts & zones– Prominent spots

• Great Red Spot• White & brown ovals

• Jupiter’s deeper atmosphere– Comet Shoemaker-Levy 9

• 23 fragments < 1 km in diameter– Galileo Probe spacecraft

• 1 tiny spacecraft for ~ 1 hour• Jupiter’s four-layer internal structure

– Ordinary gaseous hydrogen & helium– Helium & liquid metallic hydrogen– Liquid “ices” (H2O, CH4 & NH3)– Rocky & metallic core

• Jupiter’s magnetosphere– Magnetic field strength ~ 14 x Earth’s

• Circulating liquid metallic hydrogen• Very fast axial rotation

– Magnetic field size• Width of ~ 210 x Jupiter’s diameter• Length of ~ 6 AU (past Saturn’s orbit)

– Deflates quickly due to solar wind

Important Concepts: Jupiter