8Earths water may came by ice rich planetesimals Asteroids and Comets are

8earths water may came by ice rich planetesimals

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8.Earth’s water may came by ice-rich planetesimals. Asteroids and Comets are leftover planetesimals. 9. Nebula Theory: solar system formed from a large interstellar gas cloud 10. Earth: interior contain a large amount of metals such as iron {habitable because large enough to remain geologically active and distance enough to form oceans} -core(tem>6000C), mantle, crust, materials separated by density(differentiation) (20% of heat are leftover from formation, 80% from radioactive decay) heat flow leads to geological activity(volcanism, tectonics(supercontinent Pangaea)). Heat is transported by convection(plate tectonics). -atmosphere: first{H,He, leftover from the formation of the solar system}, second{vented through volcanoes and cracks in its surface, CO2(oceans soaked up half through rain), water vapor(precipitate and become ocean) and N2} third{N2, O2} -magnetic field: core(liquid iron and nickel, high electrical conductivity), axis does not align with rotation axis for around 10 degree, prevent solar wind 11. Moon: cratering shows age of surface -{highlands: covered in craters, lighter-colored}, {maria(sing:mare): few craters, darker, smooth} -tidal force: {spring tide: greatest, occurs when sun, moon, earth align, new and full moon}, {neap tide: least, occur when sun, earth, moon form a right angle}. Effects: produce tides in oceans, lock the moon into synchronous rotation, slow down earth’s rotation, increase earth-moon distance. -Formation: collision ejection theory(maybe also cause earth’s rotation axis tilt 23.5 degree, thereby creating seasons) 12. terrestrial: iron core, outer rock. More surface area, faster heat loss. Big planets cool off slower, so more geological activities. (M and V never seen far from sun) - Mercury(H, He, K, Na,O2), barren airless, crater. Scarps formd when core cooled, planet shrinking. - Venus(96%CO2{green house effect, hottest}, N2, water vapor), appears in morning or evening. Brightest after sun and moon. Water evaporate, solar ultraviolet(UV) radiation broke H2O into H and O, and solar wind strips away H atoms. Earth has ozone(O3)to shield the UV. Exhibit retrograde rotation that is opposite of the rest of the inner planets - Mars(95.3%CO2, N2, Water Vapor, other): very thin
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