NATS 1880 Chapter Notes -Tidal Heating, Exoplanet
17 May 2013
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Document Summary
Exo-planet surface life may be detected through images and spectra, but subsurface does not emit any atmosphere change. This means we do not have a chance at finding exo-subsurface life. Life can exist outside habitable zones if it gets its energy from elsewhere. Life can exist in small pockets of subsurface groundwater (mars-like) Water kept liquid due to geological conditions. Moons in outer regions contain mostly water ice. Tidal heating and radioactivity melts this ice. This allows moons with subsurface oceans to exist anywhere except close to sun. Earth size-planets internal heat can keep surface warm enough for liquid water if it has thick hydrogen atmosphere. Earth-size planets may be ejected from solar system into space. They might have thick hydrogen atmosphere that with internal heat supports life. If life can use liquid besides water, it can exist outside habitable zone. Must be big enough for atmosphere, but not too big for vertical winds.
