Habitable Zone Charts
Added 2023-07-02 21:47:51 +0000 UTCWorking on some updates to Part IVc and I liked how these hab zone charts came out so I figured I'd preview them. As a quick key:
Dry (high albedo): inner limit for marginal habitability with almost no surface water and a questionably plausible albedo of 0.8
Dry (low albedo): as above with more reasonable albedo of 0.2
Slow Rotation: inner limit for planets with slow or fully tidal-locked rotation
Recent Venus: based on the (questionable) assumption that Venus was habitable 1 billion years ago
Runaway/Moist Greenhouse: modeled inner limit for Earthlike planets due to runaway greenhouse effect
Human Tolerance: maximum distance at with a planet with an average temperature above freezing can have a CO2 level below 0.01 bar, roughly what we can tolerate for long periods
Cold Start: maximum distance at which a planet can recover from a snowball event without stalling due to CO2 condensation
Maximum Greenhouse: modeled outer limit for Earthlike planets due to formation of CO2 clouds that counteract the greenhouse effect
Early Mars: based on the assumption that Mars was habitable 3.8 billion years ago
Methane: outer limit with a 1:10 mix of atmospheric methane to CO2 (any more and reflective hazes will form)
Volcanic Hydrogen: outer limit with 0.5 bar of atmospheric hydrogen, a high but plausible estimate of what could be produced on an Earth-size planet by volcanic outgassing.
Dotted lines are based on fairly questionable assumptions, dashed lines are soft limits that probably vary a lot with planetary parameters, extent of each line represents the effective temperature range for which they have been modeled (and I truncated the Early Mars and Methane lines where they give more restrictive limits than the Maximum Greenhouse limit)
