March 12

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Astronomy & Astrophysics
Susan Pfieffer

AST251 MARCH 12 2012 LECTURE 9 WHEN WE SAY LIQUID WATER IS UNSTABLE ON MARS WE MEANMARS USED TO HAVE MAGNETIC FIELDITS ROTATION IS SLOWER MARSRetrograde is key defining feature The dots in background is Uranus moves much more slowly bc further away fainter despite bigger size then marsMars and Uranus close together indication planets in same plane follow same track as other planets and the sun Mars visibilityOpposoition as close to earth as possible good time to travel to marsMars on eccentric orbit Every two years bc mars move slowler around sun then earh does Mars oppMars essential factsAverage distance is 15 auAmount sunslight per sa down as distance squareda lot less light energy to heat planetEllipticalEccentricity measured by e closest 9 percent closer and 9 percent further dramatic difference in sunlight received198 vs 28 varies by almost 15Rotation rate is like earth 24hrs 40 min longer curious to mars rover bc active day time not night they live on a 24 hr 40 min clock on mars when rises and sets Slower but not significant Rot axis is inclined to orbit by 25 degrees like earth 235 degrees25 is current and changes earyh always around 234 decrssMars smaller then earth half radius so volume is one eight and mass is one tenthSmaller volume less gravity 40 percent that of earth moon is 16 still jum aroundGravity easier to lose atmosphere Moons of marsPhobos and deimos once said artificial by martian civ not special capture by asteroid beltIn pop culture
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