A Possible Interpretation to Venusian Rotation Evolution

Inthispaper,theauthorestimatedthelongaccelerationofVenusainrotationcausedbythe bothtorques,theNewofthesolargravitationtide,andtheFatmoofthezonalwindofatmospheric circulationofVenuswhichhasbeenmeasuredbythePioneerVenusandVeneraprobes.Taking thePrimordialperiodofanticlockwiserotationofVenusT0 =1 5hours ,thequalityfactorQ = 2 5 0 ,thelatituderangeoftheatmosphericcirculationisequalto± 70° ,andthedataoftheaver agewindspeedsandtheaverageatmosphericdensitiesindifferentatmosphericstratificationare takenfromtheheightbetween 0and 1 0 0km .Thus,thetotalrotationrateofVenuscanbeex pressedasΩ(T) =1 2 93″ +δi·1 85 6 0″sin ( 4 °5 8T0 /T) /century2 ,whereδi=+ 1for Venusiananticlockwiserotation ,δi=- 1forVenusianclockwiserotation ,Tistherotationpe riodwithunitofhour .Itcanbeestimatedthat:( 1 )thetimeofevolutionfromquickanticlock wiserotationtotheperiodoforbitalmotiontodaywithsamedirectionisaboutt1=38 5× 1 0 8 year;( 2 )changingfromanticlockwiserotationwithperiodof 2 2 4 7daysto 2 43daysclockwise today ,thetimet2 isequalto 3 1× 1 0 7year ;( 3)whentheNewappreoximatestotheFatmowith oppositedirection ,thetimewillbeestimatedexperimentallyaboutt3 =1 0 4× 1 0 9year.Itis impossibletointerprettherotationevolutionofVenusbyusingtheNewonly .