I would like to create a world that is at a roughly medieval level of scientific understanding and which - as far as it appears to the inhabitants of that world - has a highly erratic day and night cycle, with long periods of 'day' (of many Earth months in duration) and very unpredictable periods of 'night' (that would be less frequent than 'day', sometimes long, and unpredictable in length for the inhabitants of the world).
I know similar questions have been asked before (see links below) but I think my question is slightly different as I'm not looking for an ACTUALLY erratic or unpredictable day or night cycle, just something where perhaps the patterns involved are so complex and take place over such long periods of time that, to observers on the world's surface who have only medieval technology, it would SEEM erratic and random. I would, however, like to understand the science of how it might work myself so I can have a basis for working out how the population would experience things.
Here's what I thought:
The world is actually an atmospheric moon orbiting a very large planet (probably a gas supergiant) which is itself in quite an eccentric orbit around one of a pair of binary stars that are in a very complex orbit with each other, something along the lines of the image below.
That would already give a very complex pattern to SEASONS as the gas giant the moon orbited would sometimes be near both stars, sometimes near one and sometimes near neither. It would also account for there being more periods of 'day' than of 'night'.
It doesn't help with creating what appears to be a very erratic day / night cycle for the population of the moon though, so then I thought that if the rotational speed of the moon itself, as well as the speed of its rotation around the gas giant, were slow enough then there might be reasonably frequent (yet complex in pattern) periods where both suns are behind the gas giant and then the people on the moon would experience two types of 'night' over an extended period - firstly, a very dark and starless sky as they face the gas giant which is blocking out both suns and secondly a still dark but now starlit sky as they face away from the gas giant, which is still blocking out the suns. The star / no star transition might be fairly rhythmic as it would just depend on the rotation of the moon but how long the overall experience of darkness would last would presumably be too difficult for the population to know.
Such an alignment would presumably come up much less often than one in which there were either periods of perpetual 'day' (when at least one of the suns was visible whatever the rotation of the moon) or a reasonably regular day / night cycle (when at least one of the suns was visible at some point in the rotation of the moon) but - as far as I can see - could account for the PERCEPTION of an unpredictable day / night cycle with occurrences of long, extended 'nights' every now and again.
So, my questions are:
- With a modicum of handwavium, does this seem to present at least a plausible (if highly improbable!) explanation for the EXPERIENCE of an erratic day / night cycle for the inhabitants of the moon?
- If not (or even if so), any better / simpler proposals?
PS - I'm aware of the Three Body Problem but don't want the world to be regularly razed by fire, even if it might get uncomfortably hot at some points!
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