10.1 T HE C ONCEPT OF A H ABITABLE Z ONE
Exo-planet surface life may be detected through images
H OW DOES A PLANET ’S LOCATION AFFECT ITS and spectra, but subsurface does not emit any
PROSPECTS FOR LIFE ? atmosphere change. This means we do not have a chance
Habitable environments have at finding exo-subsurface life.
An energy source COULD LIFE EXIST OUTSIDE THE HABITABLE ZONE ?
Chemicals for life Life can exist outside habitable zones if it gets its energy
Liquid water (or other polar liquid) from elsewhere
Life can exist in small pockets of subsurface groundwater
Water kept liquid due to geological conditions
Life can exist in subsurface oceans
Energy sources are they only real variable Moons in outer regions contain mostly water ice
Earth’s energy source is the sun Tidal heating and radioactivity melts this ice
Only at certain range of distances will the water This allows moon