NSCI 314LIFE IN THE COSMOS11 - SEARCHING FOR LIFE IN OUR SOLAR SYSTEM:MOONS OF THE OUTER PLANETSPLUS: WHY IS PLUTO NO LONGER CNSIDERED A PLANET?Dr. Karen KolehmainenDepartment of Physics CSUSBhttp://physics.csusb.edu/~karen/DIAMETER: 20% OF EARTHMASS: 0.2% OF EARTHDENSITY: 2.1 gm/cm³SUNLIGHT: 0.06% OF EARTHTEMP: 45 K (-230 oC OR –380 oF)ATMOSPHERE: VERY THIN, METHANE (CH4) ICE CRYSTALSSURFACE: ICE AND ROCK, METHANE (CH4) ICEMOON: ONE LARGE ONE (CHARON), PLUS TWO SMALL ONESNOTE: PLUTO IS NO LONGER CONSIDERED TO BE A PLANET. IT IS JUST A LARGE KUIPER BELT OBJECT.PLUTOPLUTO AND CHARONPLUTO IS SMALLER THAN ANY PLANET IN THE SOLAR SYSTEM - ONLY 2/3 SIZE OF EARTH’S MOONMOON (CHARON) IS HALF THE SIZE OF PLUTOBOTH ARE ICY/ROCKY BODIESBOTH IN SYNCHRONOUS ROTATIONSIZE AND COMPOSITION SIMILAR TO MOONS OF OUTER PLANETS OR LARGEST KUIPER BELT OBJECTS (COMETS) WAY TOO COLD FOR LIFE (NO WARMER AREAS LIKE GAS GIANT PLANETS DEEP DOWN IN ATMOSPHERE)NO OFFICIAL NAME YETUNOFFICIALLY CALLED XENA BY SOME, BUT THIS IS UNLIKELY TO BE THE OFFICIAL NAMEDIAMETER: 20 TO 25% OF EARTH (A LITTLE LARGER THAN PLUTO)MASS: PROBABLY 0.2 TO 0.3% OF EARTHDENSITY: PROBABLY ABOUT 2 gm/cm³SUNLIGHT: 0.01% OF EARTHTEMPERATURE: ABOUT 3O K (-245 oC OR –405 oF)ATMOSPHERE: ?? (NOT MASSIVE ENOUGH TO HOLD ONTO MUCH OF ONE)SURFACE: ICE AND SOME ROCK, METHANE (CH4) ICEMOON: HAS ONE (NOT NAMED YET EITHER)NEW LARGE KUIPER BELT OBJECTTHIS OBJECT AND PLUTO ARE SIMILAR. BOTH ARE:•SMALLER THAN ALL 8 PLANETS (MERCURY THROUGH NEPTUNE)•MOSTLY ICE, SOME ROCK•ORBITS AREN'T AS CIRCULAR AS THOSE OF THE 8 PLANETS•ORBITS ARE TIPPED SLIGHTLY RELATIVE TO THE DISK FORMED BY THE PLANE OF THE 8 PLANETSSEEM MORE LIKE BIG KUIPER BELT OBJECTS •RECALL THAT THE KUIPER BELT IS THE INNER GROUP OF COMETS IN OUR SOLAR SYSTEM. (THE OORT CLOUD IS THE OTHER GROUP OF COMETS FARTHER FROM THE SUN.)NEW LARGE KUIPER BELT OBJECTTHE DISCOVERY OF THIS OBJECT PROMPTED RECONSIDERATION OF THE DEFINITION OF A PLANET. •THERE MAY BE MANY KUIPER BELT OBJECTS THIS LARGE WAITING TO BE DISCOVERED. •DO WE WANT TO CALL THEM ALL PLANETS?•IF NOT, THEN TO BE CONSISTENT, PLUTO SHOULDN'T BE CALLED A PLANET EITHER. OFFICIAL DECISION (RECENT): NEITHER PLUTO NOR THIS OBJECT ARE PLANETS. INSTEAD, THEY ARE LARGE KUIPER BELT OBJECTS (COMETS).THE RULES ASTRONOMERS HAVE ESTABLISHED FOR NAMING PLANETS ARE DIFFERENT THAN FOR NAMING OTHER OBJECTS, SO NO DECISION ON THE NAME OF THE RECENTLY DISCOVERED OBJECT WAS MADE BEFORE THE DEFINITION OF A PLANET WAS DECIDED UPON.NEW LARGE KUIPER BELT OBJECTMOONS OF OUTER PLANETSMIXTURE OF ICE AND ROCKLOTS OF THEMEACH PLANET WITH ITS MOONS RESEMBLES A MINIATURE SOLAR SYSTEMSMALL MOONS ARE IRREGULARLY SHAPED, WITH NO ATMOSPHERES, NOT GOOD CANDIDATES FOR LIFELARGER ONES ARE SPHERICAL, SOME HAVE ATMOSPHERES OR ARE INTERESTING IN OTHER WAYSCHARACTERISTICS OF LARGE MOONSPlanet NameDensity (g/cm3)Mass (Moon=1)Diameter(Moon=1)EarthJupiterJupiterJupiterJupiterSaturnNeptuneMoonIoEuropaGanymedeCallistoTitanTriton(Pluto)3.33.53.01.91.91.92.12.111.20.72.01.51.80.30.1711.10.91.51.41.50.80.65TIDAL FORCES AND THE MOONS OF JUPITERTHE SIDE OF THE MOON CLOSEST TO JUPITER EXPERIENCES A STRONGER GRAVITATIONAL PULL FROM JUPITER THAN DOES THE SIDE OF THE MOON FARTHEST FROM JUPITER.JUST LIKE WITH THE EARTH’S MOON, THIS HAS LOCKED THE MOON INTO “SYNCHRONOUS ROTATION” WITH JUPITER. ONE SIDE OF THE MOON ALWAYS FACES TOWARDS JUPITER, AND THE OTHER SIDE FACES AWAY FROM JUPITER.AS THE ORIGINAL ROTATION OF THE MOON WAS SLOWING (BEFORE THEY WERE LOCKED INTO SYNCHRONOUS ROTATION), INTERNAL FRICTION HEATED MOONS ENOUGH TO MELT THEM, LEADING TO A DIFFERENTIATED (LAYERED) STRUCTURE.TIDAL EFFECTS ON JUPITER’S MOONSTIDAL FORCES ALSO AFFECTED ORBITS, LOCKING THEM INTO “RESONANCES.”–EXAMPLE: MOON FARTHER OUT ORBITS IN TWICE THE TIME OF ONE CLOSER IN. ORBITS ARE ELLIPTICAL (NOT CIRCULAR), SO SHAPE OF MOON VARIES SLIGHTLY THROUGHOUT ITS ORBIT AROUND JUPITER.–MORE ELONGATED WHEN CLOSER TO JUPITER–MORE SPHERICAL WHEN FARTHER AWAY–THIS LEADS TO CONTINUING INTERNAL FRICTION, HEATING THE INTERIOR OF THE MOON.AS A RESULT, JUPITER'S LARGE MOONS ARE WARMER THAN WE WOULD EXPECT BASED ON DISTANCE FROM THE SUN.THE LARGER THE MOON IS AND THE CLOSER IT IS TO JUPITER, THE GREATER THE AMOUNT OF TIDAL HEATING.MAJOR MOONS OF JUPITER (IN ORDER OUT FROM JUPITER, THEREFORE HOTTEST TO COLDEST)IOEUROPAGANYMEDECALLISTOIOCLOSEST MOON TO JUPITER, SO TIDAL EFFECTS ARE LARGESTHIGHEST DENSITY - ROCKIER THAN OTHER MOONS, TEMPERATURE IS TOO HIGH FOR ICE HOT ENOUGH TO BE COMPLETELY MOLTEN INSIDELOTS OF SULFUR ON SURFACEMANY ACTIVE VOLCANOES ERUPTING CONSTANTLYMORE VOLCANOES THAN ANY OTHER OBJECT IN THE SOLAR SYSTEMNOT A GOOD PROSPECT FOR LIFE: NO WATER, LITTLE OR NO ATMOSPHERE, AND LARGE TEMPERATURE EXTREMESEUROPANEXT LARGE MOON OUT FROM JUPITER WARM INTERIOR, NOT AS HOT AS IOCOMPOSITION:–ROCKY AND/OR METALLIC CORE –SURROUNDED BY LIQUID WATER OCEAN(?) 50 TO 150 KM DEEP–COVERED BY CRUST OF CRACKED ICE 5 TO 25 KM THICK–NO ATMOSPHERE, BUT ICE CRUST PREVENTS WATER FROM BOILING INTO SPACE FEW CRATERSEVIDENCE FOR OCEAN ON EUROPAFEW IMPACT CRATERS–IMPACT BREAKS THROUGH ICE, WATER FROM BELOW FILLS IN CRATER AND FREEZESCHAOTIC TERRAIN–PATCHWORK RIDGED PATTERN OF ICEBERGS FROZEN IN PLACESTAINS ON CRUST INDICATE UPWELLING OF WATER CONTAINING DISSOLVED (ORGANIC?) MATERIALSMAGNETIC FIELD–IMPLIES PRESENCE OF ELECTRICALLY CONDUCTING LIQUID MATERIAL (SALT WATER)LIFE ON EUROPA?NO ATMOSPHERE, BUT ICE PREVENTS WATER FROM BOILING AND PROVIDES UV PROTECTION ENERGY SOURCE:–HYDROTHERMAL VENTS?–UNDERSEA VOLCANOES?–RADIOACTIVE DECAYIN INTERIOR OF MOON?–PHOTOSYNTHESIS COULD OCCUR IN POCKETS OF WATER DIRECTLY UNDER THINNER ICE? (BUT NOT MUCH SUNLIGHT)PROBABLY NO COMPLEX LIFE, BUT MAYBE SIMPLE LIFE FORMS–PROBABLY NOT ENOUGH ENERGY TO SUPPORT LARGE AND COMPLEX ECOSYSTEMSPACECRAFT MISSION PLANNED, FUNDING CUT–WILL DRILL THROUGH ICE AND RELEASE SUBMARINEGANYMEDENEXT LARGE MOON OUT FROM JUPITERLARGEST MOON IN SOLAR SYSTEMICE CRUST WITH A MIXTURE OF:–LIGHTER YOUNGER GROOVED TERRAIN (SIMILAR TO EUROPA), AND –DARKER OLDER CRATERED TERRAINMAY BE AN OCEAN UNDER THE ICE, BUT EVIDENCE IS WEAKER THAN FOR EUROPA–MAGNETIC FIELDCOLDER THAN EUROPA, SO ICE IS