Galileo and the Outer PlanetsPTYS206-2Spring 2008"All truths are easy to understand once they arediscovered; the point is to discover them."Galileo Galilei (1564-1642)The Outer PlanetsInteriors: Big H2 AtmospheresMajor Constituents0.02%0.02%NH3Ammonia~0.4% (?)~0.2% (?)H2OWater0.2%0.2%CH4Methane7%14%HeHelium92%86%H2HydrogenSaturnJupiterChemicalFormulaGasUranusAbsorption ofsunlight at redwavelengths bymethane rendersthe planet blue.NeptuneNeptune emits moreenergy from itsinterior than doesUranus. This energydrives weather. Thecolder temperaturescause methane tocondense in theupper atmosphere –these are the cloudsthat we see.Jupiter’s RingsSilicate dust, 10,000 times more transparent than window glass.Uranus’ RingsRings are made of darkmaterial, unlike ice, andpostulated to becarbonaceous.The rings are made up ofa bunch of narrow rings,separated by larger gaps.Neptune’s RingsNarrow rings of varying densityWhat causes Ring Structure?The interaction ofring particles withmoonlets.Cordelia andOrphelia orbit 2000km on either side ofUranus’ Epsilon Ring.Uranus’ rings and a couple of shepherdsOctober 18, 1989The Galileo SpacecraftTrajectory to JupiterThe Asteroid Ida and its Moon DactylJupiter’s Ammonia Clouds:Belts: Dark bandsZones: Bright bandsGreat Red SpotWhite Ovals The GRS has existed for ~300yrs. Ovals have been seen tosurvive tens of yearsBelts and Zones0.67 daysNeptune0.72 daysUranus0.44 daysSaturn0.41 daysJupiter1 dayEarthRotation PeriodPlanetRapidly Rotating PlanetsJupiter & Saturn AtmospheresJupiter’s clouds resultfrom convection.1) Hot air expands.2) Lighter than therest of the air, itrises.3) As it rises, it coolsand condensesforming clouds.4) When it is coolerthan the ambientair, it sinks.The Galileo Probein AssemblyAt what speed did the Galileo probe enterJupiter’s Atmosphere?Show Probe Movie20,000 kmThe Great Red SpotWater Cloud Thunderstorm Northwest of Great Red SpotGiant Thunder Storm on JupiterJupiter’sMoonsIoEuropaGanymedeCallistoEuropaClose-up of EuropaGrooves and RidgesA Close-up of Europa: Chaotic TerrainInterior of Europa: an Ocean of Water?Eruption on IoJune 28, 1996Lava
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