ASTRON 2B03 Lecture Notes - Lecture 20: Runaway Greenhouse Effect, Goldilocks Principle, Star System
28 Aug 2016
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Document Summary
Earth is the only location of life that we know of. Goldilocks principle looks at habitable zones around stars where liquid water could exist. Note that the location of the habitable zone changes with time. The habitable zone radius depends on the energy output of the star. The older the star, the brighter it gets, and the larger the radius of the habitable zone: in 4 to 5 billion years, the sun will become a red giant and engulf the planets around it. There could be planets ready to produce life, but they aren"t hot enough yet: atmosphere: greenhouse gases in an atmosphere is needed to hold some of the heat from starlight, acting as an insulation blanket . Too little atmosphere (like mars) huge swings in surface temperature during the day. About 4-4. 5 billion years, there were a lot of heavy bombardment of the solar system.
