How similar to earth could a planet which experiences a permanent day be?

I want to play with the idea of a sapient species evolving on a world where at least part of the world experiences a permanent day. The obvious way to doing this would be where part of the world faces the sun always and part of the world phases away, though I'm not limited to that approach so long as a reasonable portion of the world will always have day-light.

I would like to imagine a world as similar to earth as possible given this criteria; or to be more specific a world that applies the most similar evolutionary pressures that earth placed on evolving creatures; other then the obvious no-day part.

In reality I can't just say earth, but without a night. The physical world would be different. Most obvious the constant sunlight being absorbed all day would have an impact on temperature, to keep the world the same temperature the sun would have to have lower radiance or the worlds atmosphere less likely to trap heat. I think this would also encourage more severe weather patterns, particularly near the border between day and night?

Thus I'm wondering how close could a planet get to earth-like, or encouraging of earth-like creatures evolving, while having a permanent day? What are the most significant differences such a planet would have compared to earth, beyond the obvious day itself.

posted almost 9 years ago

dsollen‭

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