1. 12a. Jupiter Jupiter & Saturn data
Jupiter & Saturn seen from the Earth
Jupiter & Saturn rotation & structure
Jupiter & Saturn clouds
Jupiter & Saturn atmospheric motions
Jupiter & Saturn rocky cores
Jupiter & Saturn magnetic fields
Discovering Saturn’s rings
Structure of Saturn’s rings
Rings & shepherd satellites

2. Jupiter Data (Table 12-1)

3. Jupiter Data: Numbers Diameter: 142,800.km 11.19 . Earth
Mass: kg Earth
Density: water Earth
Orbit: km AU
Day: 9h.50m 30s Earth
Year: years Earth

4. 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 very colorful & dynamic atmosphere
Great Red Spot, belts & zones…
Jupiter’s interior probably consists of three layers…
Atmosphere: Liquid molecular hydrogen
Mantle: Liquid metallic hydrogen
Core: “Metal” & “rock”
Jupiter has 4 large & 12 small known moons
Io is the most volcanically active body known

5. 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 Jupiter’s 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 determine 9h 50m 28s equatorial Jovian day
Discovered Jupiter’s differential axial rotation
Jupiter rotates fastest as its equator

6. 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
Easily obtained spectra of CH4 (methane) & NH3 (ammonia)
Cold H2 & He are extremely difficult to detect
UV spectra in 1960
Jupiter does have a rocky & metallic core
This may have been the “seed” for the rest of Jupiter

7. Spacecraft Images Show Cloud Details
Pioneer 10 & Pioneer 11 fly-bys & 1974
First close-up images of Jupiter
Spectacular images of Galilean moons, esp. volcanic Io
Voyager 1 & Voyager 2 fly-bys 1979
Spectacular close-up images of Jovian storm systems
Additional details of most Jovian moons
Galileo atmospheric probe & orbiter 1995
Descended through a clear area in Jupiter’s clouds
Severely crippled yet still in operation in October 2002
Cassini 2000
The primary mission is to Saturn
Imaged Jupiter during its gravity-assist [slingshot] fly-by
Simultaneous observations by Galileo

8. Patterns In Jupiter’s Clouds

9. Jupiter Seen From Far & Near
Earth-based telescope Voyager 1 spacecraft

10. Five Historic Views of Jupiter

11. Jupiter’s Great Red Spot
Solar System champ
Longest lasting storm system Since 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

12. Voyager 2 & Jupiter’s Great Red Spot

13. Jupiter & Ganymede: A Family Portrait

14. 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 directly by Jupiter’s atmosphere
Jupiter’s internal heat
Jupiter emits ~ 2x as much energy as it gets from sunlight
Residual heat from Jupiter’s formation
New heat from He condensation Heat of 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 directions Zonal winds

15. 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 descending air Relatively low & warm
Zones are bands of ascending 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

16. Jupiter’s Upper Atmospheric Structure

17. Jupiter’s (Low) Belts & (High) Zones

18. Jupiter’s Cloud Colors
Distinctive “Earth tones”
Yellow, brown, pink, red…
These vary over time & space
Source of colors
All three cloud layers 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

19. Jupiter’s Deep Atmosphere: S-L 9
Comet Shoemaker-Levy 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 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

20. S-L9: The String of Pearls Comet

21. Comet Shoemaker-Levy 9 Hits Jupiter

22. Jupiter’s Deep Atmosphere: Galileo
Galileo atmospheric probe 7 December 1995
Only spacecraft to ever enter Jupiter’s atmosphere
Entry speed of ~ 49 km . sec–1 ~ 106,000 mph
Decelerated to ~ 40 km . hr–1 in 3 minutes ~ 25 mph
Descended by parachute for ~ 1 hour
Reached a depth of ~ 200 km & 24 x Earth’s air pressure
Important 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
The Galileo Probe had bad luck & entered a clear warm spot
Traces of NH3 & NH4SH clouds but no sign of H2O clouds
Atmospheric gases
Virtually identical to the Sun
Only one-half the expected amount of atmospheric H2O vapor

23. The Galileo Probe Timeline

24. Oblate Shape Reveals a Rocky Core
Even small telescopes reveal Jupiter’s oblate shape
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 the 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

25. Jupiter’s Four-Layer Internal Structure

26. 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
Powerful electric currents in Jupiter’s ionosphere
Wavelengths of a few tenths of a meter Decimetric radiation
Extremely fast electrons in a very strong magnetic field
Jupiter’s magnetic field is ~ 14 x Earth’s magnetic field
Possible causes
Hydrogen is a liquid metal above atmospheres
This pressure is reached ~ 7,000 km below Jupiter’s clouds
The “gas giant” Jupiter is mostly liquid metallic hydrogen

27. Jupiter’s Magnetosphere is Immense
Spacecraft measurements
Pioneer & Voyager
Magnetosphere is ~ km in diameter seen from the Sun
~ 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
Taken to be the core axial rotation rate of Jupiter
Galileo
Suffered extensive radiation damage in orbit around Jupiter
Basic characteristics
Jupiter’s magnetosphere is filled with plasma
Solar wind gusts rapidly deflate Jupiter’s magnetosphere
Size varies by a factor of 2

28. Jupiter’s Magnetosphere
A schematic view
A radio view

29. Important Concepts: Jupiter
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