The Satellites
• 4 Galilean Moons: Io, Europa, Ganymede,
Callisto
• 44 Named asteroidal moons
• 15 as-yet-unnamed asteroidal moons
The orbits of the moons are in resonance
with one another.
All 4 moons orbit in synchronous rotation.
Moon Data
Radius
(km)
Io
1821
Europa
1561
Ganymede
2631
Callisto
2410
Density 3530
(kg/m3)
3010
1940
1830
Orbit
Radius
(Rj)
9.4
15.0
26.3
5.9
Io
• More than 80 erupting volcanoes.
• Surface is entirely sulfur and sulfur
compounds.
• Volcanoes spew sulfur dioxide, which
“rains” back onto the surface.
– Electrically conductive sulfur and
oxygen ions escape Io’s gravity, and
orbit Jupiter in a torus.
Tvashtar Eruption Movie
• Planetary Society
The Io Plasma Torus rotates along with
Jupiter’s magnetic field, once every 10 hours.
Jupiter’s magnetic field is not aligned perfectly
with its spin axis, so the torus has a “wobble”.
A movie of the Io Plasma Torus
http://haydenplanetarium.org/resources/ava/page/index.php?file=P0404juptorus
An electrical current flows from Jupiter to
Io and back again: 2 trillion watts of power.
This current flows through the Flux Tube.
When Io is properly
aligned, this current emits
radio signals at around
20.1 MHz.
(Radio Jove Project)
Why hasn’t Io cooled off?
• Io is about the same size and mass as the
earth’s moon.
• Our moon shows no current volcanic
activity.
• Why isn’t Io in the same state?
Europa
• Salty ice crust – the flattest surface of any
planet or moon in the solar system
• Subsurface liquid or slushy ocean?
• Linea or tectonic cracks
• Few craters
Minos
Linea
Region
Ganymede
• The largest moon in the solar system
– larger than Mercury and Pluto
• Icy crust
– Older, heavily-cratered dark regions.
– Younger, lighter-colored terrain, where
liquid water has erupted from beneath
the surface.
Ganymede’s Interior
• Mottled, grooved surface
• Evidence that subsurface water has
erupted onto the surface
• A metallic core with an icy mantle is
implied.
• (Rocky outcrops under the ice)
Callisto
• Heavily cratered icy surface indicates that
the surface is original, not changed by
tectonic processes.
• This implies that Callisto may have no
core, or may be incompletely differentiated
(layered).
Palimpsests
• Palimpsest (ghost craters)
– ice rebounds slowly after impact
– crater is filled back to original surface
elevation
– leaves behind only a crater “fingerprint”
– Name comes from a re-used writing
parchment.
The Valhalla palimpsest – as big as the U.S.
Palimpsest –
a parchment partly
erased and reused.
The former ghostly
writing shows
through underneath.
Only 6 Missions
• Pioneer 10 – launched early 1972, flyby
Dec., 1973.
– first mission to pass through the asteroid
belt.
– first mission to photograph Jupiter, just
130,000 km above cloud tops.
– last signal received 2003
• Pioneer 11 – launched 1973, flyby 1979
– took photos of Jupiter & Great Red Spot
Voyager
• Voyager 1 – 1977, flyby 1980
– studied and photographed Jupiter’s
moons
– currently the most distant man-made
spacecraft, 100 A.U.
• Voyager 2 – 1977, flyby 1981
– studied and photographed GRS and
Io’s volcanism
Galileo
• Launched 1989
• Problems with main antenna, computers
• Made 34 orbits through Jovian system
• Sent a probe into Jupiter’s upper
atmosphere
• Purposely crashed into Jupiter in 2003 so
it wouldn’t accidentally crash into Europa
and possibly contaminate that moon
Galileo science highlights
• Enormous thunderstorms within Jupiter’s
upper atmosphere
• Studied Io’s volcanism
• Found even stronger evidence for
Europa’s subsurface ocean
• Found that Ganymede has its own
magnetic field
• Callisto may also have a subsurface
ocean and a magnetic field
Cassini
• Primarily a mission to Saturn.
• Made a flyby of Jupiter on Dec. 30, 2000
(the Millenium Flyby)
• Unusual that two U.S. spacecraft on
independent missions were observing
another planet at the same time.
http://nssdc.gsfc.nasa.gov/planetary/factsheet/jupiterfact.html
http://www.blue-cosmos.de/system/jupiter.html
http://www.pa.msu.edu/people/horvatin/Images/Planets/jupiter/
http://en.wikipedia.org/wiki/Image:OblateSpheroid.PNG
http://www.jpl.nasa.gov/images/sim/jupiter-earth-browse.jpg
http://www.enchantedlearning.com/jgifs/Jupiterearthsun.GIF
http://www.windows.ucar.edu/jupiter/images/jupiter_magneto_small.jpg
http://physics.uoregon.edu/~jimbrau/BrauImNew/Chap11/FG11_13.jpg
http://ase.tufts.edu/cosmos/pictures/Explore_figs_5/Chapter3/Fig3_16.jpg
http://www.astrophysicsspectator.com/topics/planets/JupiterMagnetosphere.html
http://www.space.com/scienceastronomy/solarsystem/jupiter_elements_991117.html
http://antwrp.gsfc.nasa.gov/apod/image/0311/jupiterp_cassini_full.jpg
http://quest.nasa.gov/galileo/features/data.html
http://www2.jpl.nasa.gov/galileo/graphics/230-1226B_s.gif
http://physics.uoregon.edu/~jimbrau/BrauImNew/Chap11/FG11_10.jpg
http://astro.gmu.edu/classes/a10594/notes/l20/l20.html
http://www.astro.lsa.umich.edu/~haller/ast_160/copy/jupiter_rot.jpg
http://www.windows.ucar.edu/jupiter/images/belts_zones_disc.gif
http://sse.jpl.nasa.gov/multimedia/gallery/PIA00014.jpg
http://www.universetoday.com/category/jupiter/
http://www.windows.ucar.edu/jupiter/images/J_moon_orbits.gif
http://www.mysciencesite.com/sse_moon_sizes.jpg
http://www.pa.msu.edu/people/horvatin/Images/Planets/jupiter/Io.jpg
http://www.unet.univie.ac.at/~a9503672/astro/grafiken/solar/volcano-on-io.jpg
http://vega.lpl.arizona.edu/iotorus/iotorus-frame.html
http://csep10.phys.utk.edu/astr161/lect/jovian_moons/promdisk.jpg
http://ufro1.astro.ufl.edu/iotorus.jpg
http://www.planetaryexploration.net/jupiter/io/images/jupiter_aurora_01257.jpg
http://hal.physast.uga.edu/~jss/1010/ch11/
http://www2.jpl.nasa.gov/galileo/mess41/images/min_lineargn.gif
http://antwrp.gsfc.nasa.gov/apod/image/9903/ganymede_galmosaic_big.jpg
http://slamdunk.geol.ucl.ac.uk/~brodholt/B165/Figures/Planets/chaos_europa.jpg
http://www.astr.ua.edu/ay102/Lab5/Jupiter/callisto.jpg
http://planetscapes.com/art/browse/calint.jpg
http://www.oulu.fi/astronomy/planetology/TerrPlanets/Pl1_2001/T_Suokas/valhalla.gif
http://www.dexus-hosting.cz/o-dexus/pojmenovani-serveru/_img/callisto/valhalla.jpg
http://www2.jpl.nasa.gov/galileo/graphics/rings.gif
http://www.news.cornell.edu/releases/sept98/rings/300/jupmos.GIF
http://www.windows.ucar.edu/tour/link=/jupiter/space_missions.html
http://quest.nasa.gov/sso/cool/pioneer10/graphics/lasher/slide2lg.gif
http://voyager.jpl.nasa.gov/
http://galileo.jpl.nasa.gov/discovery.cfm
http://solarsystem.nasa.gov/multimedia/gallery/galileo.jpg
http://solarsystem.nasa.gov/multimedia/gallery/Galileo_Diagram.jpg
http://www.spacetoday.org/SolSys/Jupiter/JupiterCassini.html