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Download Jupiter, Consummate Jovian - Department of Physics and Astronomy
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By the Light of Jupiter’s and Saturn’s Moons Presented by Professor Harold Geller Department of Physics and Astronomy George Mason University What I’m Going to Talk About • Moons of Jupiter and Saturn – – – – – – – – – mass diameter distance from sun chemical constituents formation atmosphere inner layers rings moons The Moons of Jupiter • Largest Moons – discovered by Galileo • hurt geocentric view of universe – Io, Europa, Ganymede and Callisto Where Are They? Moon ===== Metis ... Io Europa Ganymede Callisto … Sinope Distance (km) ========== 128,000 Distance (JD) Period (days) ========= ========= 1.79 0.29 421,600 671,000 1,070,000 1,880,000 5.90 9.38 15.0 26.3 1.77 3.55 7.15 16.7 23,700,000 332 758 (retro) Io – first volcanic eruption observed off surface of Earth • Diameter – 3640 km • Mean density – 3.5 g/cm3 • Orbital Period – 1.77 days • Mass – 1.22 times Earth’s Moon Europa • Diameter – 3130 km • Mean density – 3.0 g/cm3 • Orbital Period – 3.55 days • Mass – 0.65 times Earth’s Moon Ganymede • Diameter – 5270 km • Mean density – 1.9 g/cm3 • Orbital Period – 7.15 days • Mass – 2.02 times Earth’s Moon Callisto • Diameter – 4800 km • Mean density – 1.9 g/cm3 • Orbital Period – 16.7 days • Mass – 1.46 times Earth’s Moon Io Close Up •First discovered erupting volcano not on Earth •discovered by Voyager (1979) Io’s New Look • Considered youngest surface in the Solar System – surface is completely redone about every million years • Surface is continuously eroded by – bombardment of charged particles trapped in Jupiter's magnetic field – And volcanic eruptions Io’s Geo • What is power source of geologic activity? – tidal effect of Jupiter and Europa on Io • Tidal forces are very large – surface is pulled up and down hundreds of meters in each rotation • Is there a simple analogy? – bending a paper clip • it heats it • tidal distortions keep much of Io’s interior in molten state Io’s Geology Summary • Io has a thin crust (primarily of sulfur) – sitting on a molten interior • Molten interior breaks through surface – produces volcanoes Io’s Magnetic Personality • Io orbits within Jupiter’s magnetic field – material ejected from its surface by volcanoes (and by the charged particle bombardment from the material already trapped in Jupiter's magnetic field) • primary source of the charged particles in the Jovian magnetic field • particles (primarily sulfur and oxygen) have a high concentration in a doughnut shaped region surrounding Io's orbit - Io Torus Io’s Lightening • Io moves within magnetic field of Jupiter and through plasma torus – generates electrical current • a cylinder between Io and Jupiter of highly concentrated magnetic flux - Io Flux Tube • Flux Tube – power output of about 2 trillion (2 x 1012) Watts • comparable to TOTAL power produced on Earth – responsible for bursts of radio – frequency radiation long detected on Earth Rings and Things • A view of the ring systems – And the significance of the ROCHE LIMIT Europa • Significance due to frozen tundra – Is it liquid or solid beneath? Europa’s cracks and ice rafts may indicate a subsurface layer of liquid water Europa’s Surface Europa’s Surface Europa’s Surface Comparing Jupiter’s Moons Saturn’s Titan • Dense nitrogen atmosphere • Hydrocarbons produced by the interaction of sunlight and methane • An aerosol layer • Possible lakes of ethane Near-IR HST Images
