So, so far we know the following can alter the surface temperatures of a planet:
- Proximity to host star;
- Chemical cycles;
- Greenhouse Effect;
- Decay of radioactive elements;
- Geothermal (or volcanic) energy;
- Dense atmosphere;
- Tidal (gravitational) flexing;
and now;
- annihilation of Dark Matter particles.
If the list length increases over time and into the future, 'Habitability' will include much more of the superset of known exo-planet 'candidates'.
'Habitability' of course, may represent completely different conditions from those causing the emergence of life. We still don't know what conditions actually cause life to emerge.
Diverging the possibilities, (as this paper seems to do), serves to defocus and dilute scientific investigation.
So I'm left wondering why they've brought all this up?
Cheers
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