A recently inhabited planet revolves around its sun but does not spin on its axis. This causes the daylight cycle to happen over the course of an entire year (Note that this is different from the planet being tidally locked to its star, as there still is a slow daylight cycle.) The side facing the sun becomes superheated, while the opposite side remains extremely cold. Because this planet was recently inhabited, the residents don't have large-scale establishments, partially because they must continue traversing their way around the planet so as to stay in the small habitable zone. They travel in vehicles with rooftop gardens where they produce their food and plant-based fuel.

Presuming there is sufficient oxygen, enough bodies of water, and that the planet is close to the size of Earth, would there be any fundamental problems with a civilization attempting to lead this way of life? If so, are there also reasonable ways for this society to build permanent establishments and thrive on this planet? If not, what aspects of the planet would need to change to support at least some amount of sentient life?

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    $\begingroup$ How hot is “superheated?” $\endgroup$
    – user71781
    Dec 5, 2022 at 2:48
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    $\begingroup$ We try not to close the posts of new users, but please bear in mind: (a) Asking more than one question is a reason to close a question (you're asking 3-4). (b) We do not permit open-ended, hypothetical questions (this is both). (c) The answer to your question is, "yes, because people would have evolved to deal with it." Per the help center, questions are expected to be specific. You've not provided us with enough details to help you. (d) If you roll your mouse over the science-based and science-fiction tags, you'll see they're mutually exclusive. Please pick one. $\endgroup$
    – JBH
    Dec 5, 2022 at 3:42

3 Answers 3


It doesn't seem to be a particularly realistic survival tactic. If the inhabitants are anywhere near the equator they will have to maintain an average speed in excess of 100 km per day to avoid lagging into the hot zone. That would be very reasonable on roads (fit citizens even manage it on bicycles), but it would be hard to imagine any surface vehicle maintaining that sort of speed over mountains, valleys, rivers, seas and the generally broken ground you might expect to find on an uninhabited planet. Maybe you can get around some rough land by heading north or south, but that could significantly increase the required average speed. Vehicles tend to break down and so there would be delays for repairs. And if you don't have the spare parts you would have to abandon vehicles.

Now it would be a lot easier to move nearer the poles - for example at longitude 84 degrees (N or S) you have much smaller circles to make, which only necessitate an average speed of 10 km/day. But if you can live (get sufficient solar radiation to run your farms etc.) at that latitude, then it is probably more sensible to just migrate to the poles and stay there permanently. As the planet is not rotating, there will be no 6 month day/night cycle and it will always be twilight at the poles. So you can build permanent shelters and not risk the oblivion that would result from the inevitable irrepairable mechanical problems if you chose the nomadic route to survival.

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    $\begingroup$ + for living at the poles. But I am still digging the peripatetic rooftop gardeners!. $\endgroup$
    – Willk
    Dec 5, 2022 at 3:35
  • $\begingroup$ If such a civilization existed, they would make rapid journeys away from the poles from time to time, increasing in length and duration as their support for speed accelerated $\endgroup$
    – amara
    Dec 5, 2022 at 13:53
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    $\begingroup$ I like your point, but as a counter argument there is middle ground between living at the poles and living on the equator. Could not there be a middle ground where their close enough to the poles to allow migration to be available? if, for example, the poles are not safe to live at. Also if you assume they spend most of their time on water instead of land you could manage this, even old school sail boats easily surpassed 10 miles per hour. Fitting a garden on such a boat would be difficult, but no more then putting one on top of a ground based vehicle. $\endgroup$
    – dsollen
    Dec 5, 2022 at 16:30
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    $\begingroup$ @dsollen history.stackexchange.com/a/34378/28769 Much more difficult. $\endgroup$ Dec 5, 2022 at 18:47

If you inhibited the planet by people already travelling through space, the nomadic lifestyle becomes trivial to maintain through all the stuff available to them by starship. However, it also gets trivial to build a shelter ignoring this superhot issue altogether. So, people would pick one or the other or both - depending on what suits them, because both are about as optimal for them.

So, I am focusing more on the "how early would any of our civilizations manage that":

Pace of say 50 km/day (steppes) is doable over a pasture for say horse-based Mongols. Of course, it stops being possible the moment you need to swim; and you better already know which route avoids mountains. So, either your continent neatly splits the seas in two parts, or you are getting cooked on land. Your Vikings would be able to maintain this pace across the sea as well - there needs to be a band with much higher average wind speed (or water current) than rotation so you have enough time to dock for a while for repairs, building of new ships etc. Doing both sea and land gets possible only in modern times.

Stationary, even a caveman-tech solution exists - caves. True, shallow caves would get super-heated during the very long summer, but there are many caves that are deep enough to maintain mostly constant temperature throughout the year even in such a scenario. Grab tons of snow and ice over winter, hunt stuff through the spring and put it on the ice, have nice summer holidays, then do autumn hunt, and repeat.

Animals would probably use caves as well while the fish might get a bit deeper most of the time, going to the surface only briefly to feed. Migratory birds laugh at these issues and simply fly around. Vegetation? Well, I have no idea how that survives, temperature cycles are going to be too extreme. No plants = no animals => no food.

  • $\begingroup$ Plants would evolve seeds that survive the summer heat. They'd start near the poles, and apply more and more sophisticated techniques to be able to populate the hot zones, simply because any plant that can survive in a hotter zone has less competition for resources. What exactly plant would do with seeds would depend strongly on how "super" the heat is - e.g. a combination of sticking the seeds into the ground (maybe with a tube to the surface), insulation, and some ablative (heat-consuming) outer shell. $\endgroup$
    – toolforger
    Dec 5, 2022 at 20:17

Become a maritime civilisation

I'm assuming if this planet is sufficiently earth-like, that it has oceans. Perhaps then your people's best option then is to build sailing ships, and to sail these ships between a number of temporary settlements placed along the planet's shorelines. As an added bonus, whenever dusk falls on this planet, there will be very strong winds blowing cold dense air from the region currently under nightfall to the warmer, brighter regions to the west, which your ships would be able to take advantage of to make very swift journeys across the planet.

  • $\begingroup$ this idea is interesting the one problem is this would 1 require a passage of water that is relatively free of obstructing landmasses and 2 be large enough to not completely evaporate on the side facing the sun or freeze on the side facing away $\endgroup$ Dec 5, 2022 at 20:01

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