Night/Day Cycle

I'm trying to make a fantasy world with a longer night cycle than day.

With the advice of Renan, 12 hours of proper night, 4 hours of near/partial dark and 8 hours of good light. Similar to earth the cycle allows for entire planet to get moon and sun light in a day, but within the parameters of 12:4:8.

With this in mind the culture of the planet would be a night culture with sleep mostly occurring during the day. The main religion will be that of a lunar system with the moon being the main symbol of god, and the sun being a lesser 'evil' god and the right hand of the moon god similar to Hades.

Therefore the fauna and flora would need to be night based due to the lack of sunlight throughout the day.

Question How will this affect the way the flora would turn out? Would the plants be more geared towards a night life cycle similar but opposite to the Morning Glory?

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    $\begingroup$ You don't really need to imagine an exoplanet for that. This state of affairs occurs during the winter in the higher latitudes (arctic and antarctic) for a few months every year. If you're talking about having a longer night cycle than day CONSTANTLY, I'm not sure that's actually possible without some REALLY funky orbital dynamics. $\endgroup$ – Morris The Cat Aug 30 '18 at 19:18
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    $\begingroup$ Do you want this to be a permanent feature, or just happening during some time of the year? $\endgroup$ – L.Dutch - Reinstate Monica Aug 30 '18 at 19:20
  • $\begingroup$ Being that the world is fantasy in nature i'm not too worried about orbit, or anything outside the planet. The longer night cycle would be constant, ideally. $\endgroup$ – Celgiek Aug 30 '18 at 19:25
  • $\begingroup$ Welcome to worldbuilding. This is too broad of a question to answer in a few paragraphs. The amount of things that could be different between physical enviornment and life is vast. Please narrow this question down to ask about only certain things, such as photosynthesis or rainfall or something. Also important is that this is a fantasy world. Do you expect the laws of physics to be followed? In that case you need to explain the parameters of your day and night. Is the whole planet like this? Is the day just as bright as it is on Earth? $\endgroup$ – kingledion Aug 30 '18 at 19:30
  • $\begingroup$ Kingledion, i will fix this thank you for your advice $\endgroup$ – Celgiek Aug 30 '18 at 19:36

The planet has an atmosphere different than ours. The gases at the uppermost layers cause extreme refraction of visible light.

When the sun is high in the sky some light makes it into the surface of the planet. But when it is close to the horizon, very little reaches observers. It might be so dim as to seem it is not there at all.

Hence you get twelve hours of proper night, four hours of sun-above-horizon-but-light-deflected and finally eight hours of good light.

This will also make the horizon seem much closer and way distorted for an observer on the surface.

  • $\begingroup$ this answers my original problem with how the day and night cycle actually works. $\endgroup$ – Celgiek Aug 30 '18 at 20:19
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    $\begingroup$ This would require either a highly exotic (essentially, magic) atmosphere with a negative index of refraction, or some (still magical) effect to make the outer layers of the atmosphere denser than the lower ones. Otherwise, the normal action of atmospheric refraction is to extend daylight hours. Rather than refraction, it would make more sense to rely on absorption: when the sun is overhead, appreciable amounts of light can get through on a relatively short path down through the atmosphere, but at shallow angles almost all light is absorbed. $\endgroup$ – Logan R. Kearsley Aug 30 '18 at 21:09

Your flora would have to gather more energy per day than earth plants do, so they may have wider leaves, and wider tops. Most plants would be smaller than terrestrial plants, though some may be super large, taking advantage of the lack of competition to spread out very huge using a more efficient process not yet gained by other plants.

Fungus would be prevelant, owing to plants creating almost solid shade during the day. Slime molds in water bodies may be particularly common. The super large plants may have several types of parasites besides specialized predators.

More animals will become nocturnal, since they can forage more at night than day. The higher level of competition may lead to many animals choosing one specific food source and out competing generalists. That means any particular species may go extinct if their food source dies off.

The oceans, if you have them, may be a lot less lively than our oceans do to a lack of phytoplankten, but besides a decrease biomass it will probably be much the same.

  • $\begingroup$ What types of parasites and specialized predators would you suggest? What about luminescent plants or animals like on Pandora? $\endgroup$ – Celgiek Aug 30 '18 at 21:36
  • $\begingroup$ Well specialized predators would just be a bug that only eats one type of plant, like monarchs on milkweed. Parasites would be be things like a fungus that grows in a plants roots, or bugs that live under the bark of a tree and eat the wood. As far as bioluminecence, there may be more than on earth, but mostly in bugs. Some mushrooms have bioluminesence, but we don't really know why, so its unlikely that many more would be bioluminecent on that planet. Bugs would definitely have more, maybe double or more but its hard to say. Maybe compare bioluminesence on reefs compared to deep sea. @Celgiek $\endgroup$ – Clay Deitas Aug 30 '18 at 21:51
  • $\begingroup$ the maps i have drawn out have one major ocean and a large lake similar to that of the Black Sea. as well as lots of rivers. How would the sea life of these ecosystems be affected by the night/day cycle? $\endgroup$ – Celgiek Aug 30 '18 at 21:59
  • $\begingroup$ @Celgiek The ocean would be largely similar to ours, maybe with smaller amounts of any given species, but the lake might suffer more. Less diversity of fish, but plenty of slime molds and allgies. A good reference for you might be the rainforest, which has a lot of tree cover and near perpetual shade. However top down ecosystems like that will suffer from less light, so basically you just have smaller population sizes of anything higher on the food chain. $\endgroup$ – Clay Deitas Aug 30 '18 at 22:15

The world is flat, surrounded by incredibly high mountains, and the sun circles the world. From the time the sun drops below the top of the western mountains until the time it hits the top of the eastern mountains, it's night.


Around the Equator, tall trees with large leaves would most likely form a very large and thick canopy. These will be heliotropic (pointing towards the sun during day). The plants will need to have high levels of chlorophyll simple to make up for the minimized sunlight. Upwards of the equator, smaller and wider plants should grow.

Since the plants can't make as much energy, more than likely some would be carnivorous or live in mutualism with other species during the nighttime. There is one example of a possible formation of a carnivorous island of algae in Yann Martel's book Life of Pi, which is possible on this planet. Carnivorous vines should play a role in the ecosystem. Possibly underground plant configurations will form, sustained by a chemical in the environment.

This brings up another question: If fauna can sustain itself through the normal trophic system on Earth today, or will chemosynthesis be prevalent and all fauna originate from sea vents? Life will probably have to have some photosynthetic producers and some chemosynthetic producers to have any ecodiversity at all.

Further research on life systems might be needed, but overall I hope this helps!


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