Trying to form a mostly logical basis for a world that would have one region always in darkness while also having a day-night cycle.
My first thought was to ask if a planet could have an axial tilt always facing away from its star, but upon reading other questions on the site it seems that's not possible.
My most recent idea is a moon that is tidally locked to its planet with its rotation around its planet just happening to correspond with the time the planet's orbit takes around its star. Don't know if this is logically possible?
Thoughts on that idea and/or any other possible explanation for such a world?
P.S. Just read about precession while writing this post, but it seems that would be is the realm of millennia on such a planet to reasonably occur although the length of year on this world can be just about anything if it allows for this to work and for the planet to be habitable.