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Duality
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so I was listening to this song and a thought occurred to me: Earth's sun and moon look almost exactly the same size in the sky, but there is no natural reason for this, it's just an incredible coincidence which I think is so cool. Apparently the sun is 400 times as wide as the moon AND 400 times as far away. This is very unlikely and very satisfying
but as I was typing all this another thought occurred to me: IS it a coincidence? Since there is a such a thing as a "habitable zone," i.e. a planet can only support life if it is a certain distance from its star, it's reasonable to think that on any hypothetical life-supporting planet, one's star looks approximately the same size in the sky as the sun does to us. But what about the moon? Is there a correlation between a celestial object becoming a moon to a planet and this moon's mass/distance from its planet (i.e. its size in the sky)? Maybe not but that got me curious about how big various moons in our solar system look in their respective planets' skies. And someone made a thing about that which was really cool to see: http://umich.edu/~lowbrows/reflections/2008/jmaguran.1.html
That link has some really fascinating information I thought, especially in the table at the bottom. For the moons in the table, I calculated the correlation between their distance from their planet and their diameter. The correlation coefficient was just -.17, which is pretty weak with a sample size of 23 observations. So it does seem to be just a coincidence that our moon looks like a very similar size to our sun
interesting stuff idk i should probably be asleep or doing something productive
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The moon-sun coincidence is right up there with us being exactly halfway in size between stars and atoms in my books.
I mean think how different celestial religions would've been if the moon was smaller than the sun or if there was more than one moon. Night-Mother goddesses and Day-Father gods are almost a staple of ancient Middle East mythologies, and we probably wouldn't have Celestia and Luna in the same dynamic either.
Literary and mythological archetypes that form the foundation of much of our storytelling could've been completely different if our existence was only slightly tweaked - the fire/water/earth/air conception of elements couldn't exist without our type of biochemistry, the correspondence of up to transcendence and down to carnality probably would be inverted if our bodies were more suited to living underground, and the idea of the primordial ocean of chaos from which everything else took shape likely wouldn't exist if we didn't have oceans covering most of our planet.
Also, most planets in a habitable zone don't actually have the sun the same size in their sky! Stars vary massively in light output relative to their size so blue stars would have to be much further away from their planets than red stars of the same size. The sun is pretty average in terms of light output but yellow mid-sized stars like ours are far outnumbered by redder dwarves where planets would have to be much closer for anything to survive. Probably the most common Goldilocks zone planets would have the sun many times larger in the sky than the moons (if they even have moons) - all of the planets in our solar system with any decently sized moon in their skies are gas giants large enough to attract extremely large chunks of rock very close.
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