10.3 Surface Habitability Factors and the
Where are the boundaries of the Sun’s
What factors influence surface habitability?
The role of distance from a central star Habitable Zone today?
Inner boundary marks place where runaway greenhouse
is triggered whereas outer boundary mars surface water
When considering minimum distance, we must account
solar heating and resulting processes that evaporate freezing.
The outer boundary marks place where surface water will
When considering maximum distances, we must consider freeze.
processes that weaken greenhouse warming.
Taking account only runaway greenhouse effect, habitable
Brighter stars have wider and distance habitable zones.
inner boundary is 0.84 AU
Dimmer stars have narrower and close-in zones.
However, moderate warming might cause some water to
Brighter stars are short-lived which may not give enough circulate at higher altitudes where it is broken by UV light,
time for biology to develop.
allowing more water to rise, which depletes ocean