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Jupiter
Thursday, February 10, 2011
Vital Statistics
• 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.
Thursday, February 10, 2011
A bit of background• 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)
Thursday, February 10, 2011
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)
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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 eastThursday, February 10, 2011
Series of picturestaken by HST between1992 and 1999
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Movie interlude
• http://www.nineplanets.org/pxjup.html• look at Jupiter “Day”• Rotating Jupiter• Red spot
Thursday, February 10, 2011
Visits
• Pioneer 10 in 1973 (1st visit)• Pioneer 11• Voyager 1• Voyager 2• Ulysses (was really just using Jupiter for a
gravity boost)• Galileo
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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
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Thursday, February 10, 2011
Voyagers
Thursday, February 10, 2011
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
Thursday, February 10, 2011
Galileo
Thursday, February 10, 2011
Galileo
• 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
Thursday, February 10, 2011
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)
Thursday, February 10, 2011
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”
Thursday, February 10, 2011
Atmosphere
• Upwelling in zones, sinking in belts• high pressure in zones (low in belts)
Thursday, February 10, 2011
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)
Thursday, February 10, 2011
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
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Thursday, February 10, 2011
Internal structure
• This diagram is based on Voyager data and theoretical modeling
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Auroras
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Rings
Galileo image - clearly shows radial structure that had only been hinted in Voyager images
Thursday, February 10, 2011
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
Thursday, February 10, 2011
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
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• 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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