Jupiter
Vital Statistics
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R = 71,492 km
M = 1.90 x 1027 kg
Rorbit = 778.4 x 106 km
T = 124° K
Eccentricity = 0.048
axial tilt = 3.08°
“day” = 9.84 hours
“year” = 11.86 years
orbital inclination = 1.31°
• 11.21 RÅ
• 317.8 MÅ
• 5.2 A.U.
A bit of background
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Known since prehistoric times
One of Galileo’s 4 big discoveries
63(?) moons to date
moons are named for figures in the life of Zeus
(mostly his lovers)
• faint rings
• gradually slowing down
• Io, Europa, and Ganymede are locked in a 1:2:4
orbital resonance (in a few million years, Callisto
will be locked as well, with an orbit 8 times that
of Io)
Claims to fame
• Largest planet in the solar system
– so large that even causes a wobble in the sun’s
motion that would be detectable from other
stars
• Boasts the most geologically active moon
in solar system
• Great Red Spot
• visible bands (even visible from Earth with
backyard telescopes)
The Great Red Spot
• Origin is unknown
• A storm about 2 times Earth’s diameter
• Has been raging for at least 300 years (Discovered
by either Cassini or Robert Hooke in the mid-17th
century)
• gas flow around the spot is counterclockwise, with a
period of about 6 days at speeds up to 2770 mph
• center is tranquil (like the eye of a hurricane)
• gas north of the spot flows westward, whereas gas
south of the spot flows east
Series of pictures
taken by HST between
1992 and 1999
Movie interlude
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http://www.nineplanets.org/pxjup.html
look at Jupiter “Day”
Rotating Jupiter
Red spot
Visits
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Pioneer 10 in 1973 (1st visit)
Pioneer 11
Voyager 1
Voyager 2
Ulysses (was really just using Jupiter for a
gravity boost)
• Galileo
Pioneers
• 10 was 1st to Jupiter - just a flyby
• Pioneers were designed to test the ability of
spacecraft to survive passage through the
asteroid belt and Jupiter’s magnetosphere
• 11’s power supply is dead, but 10 is still
functioning
• will be 1st craft to reach interstellar space
– bear plaques trying to convince aliens we’re
intelligent
Voyagers
Voyagers
• Voyager 1 launched Sept 5, 1977 and flew past Jupiter
March 5, 1979
• Voyager 2 launched Aug. 20, 1977 (before V1) and
flew by Jupiter August 7, 1979
• Most of what we know about the gas giants comes
from Voyagers 1 and 2
• Discovered
– that Jupiter has complicated atmospheric dynamics,
lightning, and aurorae
– 3 new satellites
– ring system
– Io has active sulfurous volcanoes
Galileo
Galileo
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Launched Oct 18, 1989, arrived 1995
1 slingshot around Venus, 2 around Earth
Tested instruments while at Venus
High-gain antenna didn’t open as planned,
so they reprogrammed the computer to use
the smaller antenna (and we got most of the
data it sent)
• Discovered a “moon” orbiting the asteroid
Ida
Galileo
• In 1994, could see Shoemaker-Levy 9 crash into
Jupiter
• Spacecraft (orbiter) and probe
• Probe descended 95 miles, collected 58 minutes of
data on weather
• appeared that atmosphere is dryer than we thought
(but later we realized the probe had entered a hot
spot)
• near end of 58 minutes, probe measured winds of
450 mph (melted and vaporized shortly after that)
Structure and Atmosphere
• Atmosphere: 86.1% H2, 13.8% He
– also: ammonia, methane, water vapor
• Presence of lots of H2 and He is a result of strong
gravity
• Bright “zones” (other gas planets have them, but
they’re most pronounced on Jupiter) and dark
“belts”
Atmosphere
• Upwelling in zones, sinking in belts
• high pressure in zones (low in belts)
Atmosphere - Zonal flow
• Underlying the bands is a
stable pattern of eastward
and westward wind flow,
known as “zonal flow”
• note: belts and zones are
related to zonal flow
pattern
• Note - equatorial regions of atmosphere rotate faster than the
planet - average flow speed of about 85 mph (similar to
Earth’s jet stream)
Atmosphere - structure
• None of the gases listed
earlier can account for
coloration
• We believe cloud colors
are the result of complex
chemical processes
• A model based on available
data and some math
• Galileo probe made it to the
bottom of this diagram
Internal structure
• This diagram is based on
Voyager data and
theoretical modeling
Auroras
Rings
Galileo image - clearly shows radial structure that had only been hinted
in Voyager images
Moons
• Ganymede, Callisto, Europa, Io
• Metis, Adrastea, Amalthea, Thebe
• Leda, Himalia, Lysithea, Elara, Ananke,
Carme, Pasiphae, and Sinope
• At least 47 others, some of which have been
named
Ganymede
• Largest moon in
Solar System
• Weird grooves
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Callisto
• Oldest, most cratered surface of any body in
Solar System
• uniform interior of ice and rock mixture
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Io
• Very close
to Jupiter
• Active
volcanos
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Europa
• Only other body in
Solar System with
liquid water
• VERY smooth
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Europa interior