I've been wondering if it's at all possible for a habitable tidally locked planet to not be a scorched wasteland on one side, an oasis in the twilight, and a frozen wasteland on the other, the planet instead having only one side of it be uninhabitable by being frozen while the sun-facing side is lush and green and full of life.

The planet is earth-like, from its mass to its atmospheric content and even its water and elemental content(materials like iron, silica, etc), in all respects except for it being tidally locked with the star of its solar system and having no axial tilt. The star of the system is also exactly like our sun. There is a moon that's the same as ours orbiting this planet at the same distance and orbital speed as ours as well, though its orbital path has a tilt of 23 degrees to prevent excessive eclipses.

At what distance from its star must this tidally locked planet be for the sun-facing side to be forested/entirely habitable while the dark side is frozen and uninhabitable?

  • $\begingroup$ If the planet is the same as Earth and the star the same as our Sun, tidal locking won't happen any time soon $\endgroup$
    – L.Dutch
    Nov 11, 2021 at 12:03
  • $\begingroup$ Even if a planet were made that way artificially, it's not likely to stay that way for long as the light side would get all its water re-distributed to the dark one. $\endgroup$ Nov 11, 2021 at 12:55
  • $\begingroup$ @ARogueAnt. Would not the likely formation of an ice wall/glacial barrier past the twilight zone into the dark side prevent this? $\endgroup$
    – Lemming
    Nov 11, 2021 at 13:08
  • $\begingroup$ I'd say it would likely be a symptom of it. (But others may know better). $\endgroup$ Nov 11, 2021 at 13:11
  • $\begingroup$ Note even the sunward facing side won't have such a simple climate and you'd get a spread of different regions. $\endgroup$ Nov 11, 2021 at 18:39

1 Answer 1


All the planet needs to do to technically be tidally locked is have a rotation period the same as the orbital period so that one side always faces the star, like how Titan spins once every orbit around Saturn. So have the planet spin once every 365 days and it will be tidally locked and still have low enough temperature to have earth life. But having the dark side be uninhabited is a lot harder if your planet has lots of wind because wind would bring hot air to the cold side and cold air to the hot side, making the cold side only slightly colder so your planet would have to have nearly no wind.

This post on astronomy.se is about tidally locking earth and might help you a bit.

  • $\begingroup$ An atmosphere will know where the hot air is and where the cold air is; this post is good. The lush world will have some nasty weather. $\endgroup$
    – Vogon Poet
    Feb 18 at 4:40

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