Week 7 Thursday, 6 September 2018 10:14 AM WORKSHOP - Water is lighter in solid state - less dense - ice floats - water freezes into a lattice surface - ice stays on top - insulates the inside of ocean thermally - life is able to survive - Early solar system - lots of impacts from outer bodies - Jupiter attracts some of the comets and asteroids coming from the Kuiper belt - protects us from large impacts - moon does the same but on a more local ground - it has enough gravitational pull to divert or deflect the asteroids and comets effects of impacts - mass extinction - dinosaur extinction - tsunamis - lot of chaos and volcanism(maybe) having Jupiter there as a centre of mass can also make things worse and direct the short period comets towards earth - for other systems like Travis (has all low-similar mass planets) the comet is likely to circle around back to its origin as no plants are heavy enough to attract or divert the comets. - Stable rotational axis - keeps climate steady - important to develop complex life - moon helps stabilise axis since it counteracts the pull from Jupiter - Venus spins so slow that it is also very stable - not unique to Earth - CO2 cycle keeps atmosphere stable : heat atmosphere and CO2 is taken up by oceans so that earth cools - cool atmosphere and CO2 is released so that earth warms up - crucial part is geological activity of earth - Magnetosphere protects us from radiation - radiation dissociates water into body - causes mutation in the cells. Venus is outside of earth and doesn't have magnetic field most likely due to its slow spinning - in theory it should - Earth-Moon system is unique - not all planets have moons - inner rocky planets do not have moons this big - rocky planets in theory are not expected to have moons since they are so small and hence cannot attract large bodies like our moon - we have tides because of the moon - newton's gravitational law - force of g drops as r2 - rotational influence from moon is exerted on rocs but since water is easier to stretch as its liquid, we experience tides - if we didn't have moon the sun would be responsible for tides but they would be much, much weaker. - Tidal friction - moon is tidally locked - earth-moon distance increases by 4cm/year - moon was spinning faster at first - it is slowly moving away from us and is slowing us down - it is slowing us down too - so small that sun would go into red giant much faster before earth becomes tidally locked - Moon has a layer of powdered soil on the surface - why? - It is the result of countless tiny impacts by small particles striking the Moon. ASP1022 Page 2
