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Comments on Could there be a way for a solar system to be very precise, so that the lunar calendar and solar calendar align?

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Could there be a way for a solar system to be very precise, so that the lunar calendar and solar calendar align?

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I know that this is a bit silly, but I want to make a calendar for my world and I'm really worried about having to do leap years and such to ensure continuing accuracy.

Inaccuracy isn't an option; many worlds could simply have a calendar that gradually gets out of line, but the people in this world are very particular about things being easy to understand yet accurate and informative. This would extend to their calendars, I'm sure.

So, I think that the effects of gravity on other planets can affect rotation - I believe the moon is slowly slowing Earth down, right? So, would it be feasible for the sun and planet to influence each other to make sure that years are a whole number of days and that years are a whole number of months?

(This sounds like a stretch, even to me, but might be something about the frequencies of the minor oscillations in orbit plus some other factor - I have limited knowledge of any physics at all, let alone orbital mechanics, so someone smarter than me might know something.)

Secondly, could it be possible for this to occur for a planet that is a binary planet? My system is quite lopsided, the centre of the two planets' orbit is only JUST outside of the main planet, but it is still enough to be a binary planet.

(If this is impossible, advice on creating a simple yet highly effective calendar for these very fussy people would be nice.)

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Something you may not have thought of: the Earth-Luna system has the barycenter inside the Earth's radius. Fairly deep inside, in fact -- about 25% of the way down from the surface.

Your system as described is less binary-like than our own. Either the moon is smaller than Luna, or farther away, or both.

Options:

  • Change the fictional setting. Figure out the desired effect, and engineer it to produce that result.

  • Months aren't important at all to your civilization. Seasons (assuming significant axial tilt or wild orbital eccentricity) might be the preferred unit, and there's no reason to arbitrarily claim four seasons. Perhaps there are only 2, or they really like some other number -- even seems more likely than odd to me, but perhaps they have some cultural specialty for 5.

  • The moon is small and close and therefore fast: in another million years it will be a disaster, but right now it's a speck that is sometimes visible in the daylight, and has visible motion if you have any sort of reference tree or mountain.

  • The moon is large and far away -- so far away that it's in the L1 or L2 point, and is either always shading a chunk of the planet (weather effects will be interesting!) or always in the planet's shadow and thus only detectable by occluding other astronomical objects (mythological effects will be interesting!).

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2 comment threads

Stability of a fixed moon shadow (1 comment)
Oh, sorry! I mean MORE binary. While our planet has the barycentre inside the earth, this world might... (1 comment)
Oh, sorry! I mean MORE binary. While our planet has the barycentre inside the earth, this world might...
Bianca_Railway‭ wrote over 1 year ago

Oh, sorry! I mean MORE binary. While our planet has the barycentre inside the earth, this world might have the barycentre around 100 km above sea level.