Hmm. So, how possible is it for there to be life on a tidally locked world? Like, if it was orbiting a red dwarf or something, and was close enough to be tidally locked but still only got as much light as earth, would it be possible for there to be life? Maybe a thin habitable ring around the edge of the sunlit area? or would it just not be possible to have a viable atmosphere? :/
@Angle My understanding is if the planet's got a short enough day/year, the atmosphere can rotate enough to leave moderate temperatures worldwide. But that requires a dim star so the planet can support a short day/year.
Given extremophiles I'm not sure very moderate temperatures are needed.
@Austin_Dern Hmm, gotcha. What about something a little crazier? With permanent glaciers and deserts, and constant rivers traveling from the dark side to the light?
(Also, what do you wall the various places? dark side, light side...? I keep wanting to call the ring the equator, but I know thats not right. :/
@Angle (Without doing the work, I would *think* the exact terminator line would move slightly as the planet follows its elliptical orbit. That's a hunch though and shouldn't be confused with actual analysis. But it offers ecological niche potential, if it happens.)
@Austin_Dern Oooh, thats really cool. I had not considered that, I like it. It allows for something resembling seasons. XD
@Angle I don't know, but apparently there's numerical support for a livable spot on the sunlit side: https://arstechnica.com/science/2013/12/full-atmosphere-ocean-model-of-a-rotationally-locked-exoplanet/
Casual searching makes me think we're discovering lots of configurations aren't actually impossible. Not sure how many of them will be knocked out later, but there's grounds for play right now.
The ring separating the light and dark halves of a planet is the 'terminator'. I'd expect the prime meridian to be the terminator's average position over a full orbit.