太阳系的行星

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1、TheSolarSystem1star98planets63(major)moonsasteroids,comets,meteoroidsHowareplanetsizesdetermined?Measureangularsizeonsky,Thenusegeometry…..ThedistancestoplanetsareknownfromKepler’sLaws(oncecalibratedwithradarrangingtoVenus)UsingangularsizetogetactualsizeMasses-determinedthroughobservingthegravi

2、tationaleffectoftheplanetonsomenearbyobject(moons,nearbyplanets,satellites)Density-dividemassbyvolumePlanetsorbitthesuncounter-clockwiseasseenfromtheNorthCelestialPole.AllplanetsareinthesameorbitalplaneEXCEPTMercuryandPluto.TerrestrialPlanetsMercury,Venus,EarthandMarsClosetoSunSmallmasses,radii

3、Rocky,solidsurfacesHighdensitiesSlowrotationWeakmagneticfieldNoringsFewmoonsJovianPlanetsJupiter,Saturn,Uranus,andNeptuneFarfromSunLargemassesandradiiGaseoussurfaceLowdensitiesFastrotationStrongmagneticfieldManyringsManymoonsTerrestrialplanetsJovianplanets(andearth)OTHERSOLARSYSTEMOBJECTSAstero

4、ids-rockswithsizesgreaterthan100macrossMostasteroidsremainintheAsteroidbeltbetweenMarsandJupiterbutafewhaveorbitsthatcrossEarth’spath.ThreeasteroidshittheEarthevery1millionyears!KnownasteroidimpactsitesAsteroidsizesrangefrom100mtoabout1000kmTheyarecomposedofcarbonorironandotherrockymaterial.The

5、Asteroidbeltisagroupofrocksthatappeartohaveneverjoinedtomakeaplanet.Whydowethinkthis?ToolittlemasstobeaplanetAsteriodshavedifferentchemicalcompositionsIt’sallJupiter’sfault…..Meteoroids–interplanetaryrockymaterialsmallerthan100m(downtograinsize).calledameteorasitburnsintheEarth’satmosphereifitm

6、akesittotheground,itisameteoriteMostmeteorshowersaretheresultoftheEarthpassingthroughtheorbitofacometwhichhasleftdebrisalongitspathMeteorcraternearWinslow,AZ-theculpritwasprobably50macrossweighing200,000tons!Meteorsarerocky-mainlyironandnickelSomecontaincarbonaceousmaterial-richinorganicmateria

7、lMeteorsareold-4.5billionyears-basedoncarbondatingMeteorshowers:Orionid–Oct21/22Leonid–Nov18/19Geminid–Dec14/15CometsDirtysnowballs-dustandrockinmethane,ammoniaandiceHalley’sCometin1986AlllightisreflectedfromtheSun-thecometmakesno