something that wrinkles my brain every time I remember it is the fact that total eclipses are only possible on earth because the moon and sun appear to be the same size in our sky, due to the insanely, astronomically unlikely fluke that the moon is 400x smaller than the sun but 400x closer to us.

April 10, 2026 - 17:55 UTC

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Actually, if the moon were any larger than it actually is we still would have total eclipses.
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Thanks to totality, we were able to prove gravity lensing.
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Yeah this fucks me up too - very simulation
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Not only just on earth.
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Yes, and sound waves are human scale, amazing.
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I went to fact check this because I knew the moon couldn’t be only 400 times smaller than the sun but I see that it’s true that the diameter of the moon that is 400 times smaller than the diameter of the sun, and the moon is 400^3 times smaller than the sun in volume
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I also wonder if we would have a space program, calendars, and an understanding of physics if we had a cloud filled atmosphere that blocked the sight of the moon and stars. If our ancestors hadn't looked up and dreamed and tried to make sense of the motions of celestial objects.
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We’d still have calendars in some form because of women needing to keep track of their cycles and farmers needing to keep track of the seasons. Definitely couldn’t imagine astronomy though.
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Diane Duane had a fun bit where a Romulan discusses solar eclipses with humans and says essentially "and you're all atheists, huh? wow."
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….and that soon Earth won’t see any more because the moon is moving further away. You and I, by some fluke, just happen to be here during that astronomically unlikely moment.
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I mean, not for another 600 million years. The human race probably won't be around that long let's be real
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Which is an extremely cool moment to be able to witness! Especially when everything seems to be rapidly disintegrating.
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well "soon"
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no T-rex ever saw a full lunar eclipse...😢
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Soon doing a lot of heavy lifting there.
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Anthropic principle. If they were a different ratio we would explode.
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Perfect alignment of moon and sun yet the year isn't divisible by the day. Smh
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The moon is also leaving because it's had enough of drumpfs bullshit
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I ❤️ space nerds
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It's the one thing about earth that could persuade me there's some intention at work. But then I remember the Texas Sharpshooter Fallacy: if you focus too much on the inevitable coincidences, you see connections where there are none.
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THIS.

Oh, if human beings had a better handle on statistics/odds (and logical fallacies), then LOTS of things would no longer seem miraculous or 'beyond chance' ☺️
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Unless of course such a moon is necessary for life to evolve this far. If there weren't any tides, maybe we would all have stayed in the oceans :-)
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Three kids near here just got killed in a car wreck. They went to a Christian school. The principal was all calling on God to lift up their families.

I’m sitting there wondering why you keep following that God when he has the power to lift people up but not stop a fiery crash.
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Right??? Super freaky!!
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@astrokatie.com holy hell??
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The moon just has to be large *enough*, right? It doesn't need to fit perfectly.
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This fact would be the only acceptable intelligent design argument i would accept
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the other amazing piece to consider is our lucky time period.

the moon was once 10-15 times closer to the earth so it would have completely blocked the light and the corona during an eclipse.

in the future eclipses will not be total as the moon moves farther away from us. only now is it just so.
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The combination of it being that distance, and not orbiting in an exact plane with the sun means you don't get all annular/total eclipses or have them once a month in the exact same place.
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Well, you could turn it on its head: Our not so distant ancestors will have seen this phenomenon and may have started wondering about this phenomenon that's not as readilly explained as other day to day natural phenomena. I like to think this set of a cascade of wondering, which is why ...
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The Doctor towed the moon to its place
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@25kv.bsky.social
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Between that and the fact that the Moon rotates at a speed that means it always presents the same side to us, I don't know what's going on.
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Tidal locking is actually fairly normal to occur over (a very, very long) time. Not really a coincidence, just typical forces at work. Lots of moons do it.
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The moon is tidally locked.

It was spinning at the start and then slowed down because the earth's gravity was causing the shape of the moon to distort. This bending caused friction so the Moon bled off its kinetic energy as heat until the system reached the current equilibrium.
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This is really great piece (with graphics) on how the moon became tidally locked (always the same side facing towards Earth) and why it's quite common
science.nasa.gov/moon/tidal-locking/
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Eh tidal locking is decently common
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Total solar eclipses used to be far more impressive in earlier human history - the moon was closer and therefore blocked even more of the sun. It's all dope as hell!
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Not that much closer. Humans haven't been around that long in the grand scheme of things.
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Bit that boils my brain is you can fit every other planet in the solar system between the earth and the moon.
We wouldn’t have an atmosphere and we wouldn’t even be here in that instance but it would look cool
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Like, in a line, or all bunched up?
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That’s no moon…it’s a space station!
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Not to mention that from what we can tell our moon might be unusually large with respect to its planet than most moons. Granted we have a relatively small sample size to look at.
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Fun fact: In the southern hemisphere, during a full eclipse, the sun eclipses the moon
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The claim in the OP is likely wrong.
Saturn’s moon Pandora is the right size to just block the sun, from the official “surface” of Saturn.

Also, standing on any of the larger moons of the gas giants, other moons may eclipse the sun’s disk, but those events are probably extremely rare.
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It's because perfect eclipses open the gateway to Hell, just as God intended.
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Technically, the almost match allows for annular eclipses. Total eclipses would be possible if the moon appeared to be much larger than the sun just as they are possible with the close match
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And in some solar eclipses the moon does appear larger than the sun
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Thank you for making this pedantic point so I don’t have to
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I can explain this!

The oscillating frequency of the earth moon and sun roughly average out over time, and the moon is pretty low density, so it found a roughly equal point in time space.
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I'm not good enough with astrophysics to fact check this, but the immediate question that arose was then ... why wouldn't other moons do the same thing around their planets then? If this was true for our moon, wouldn't we see Phobos and/or Deimos get closer to Mars to create same effect?
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I get annoyed when people suggest anything about the natural world proves God exists, because the whole point of faith is not to need proof, but I do sometimes think of eclipses as a cheeky wink from the Almighty
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See comment 'not surprising we have big moon because planet without big moon might have unstable access making anything more complex than algae unlikely'
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Certainly, if a divine being were going to give us some weird clue as to our significance, this is a pretty darn good one. But what does it mean? Let’s have a war to find out!
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I love the idea that yes the universe is totally random, and I am happy in my atheism, but I would laugh long and hard if it turned out that *this* particular thing was God’s Easter Egg. I have been wondering about this coincidence since my teens. I accept the randomness, but I’m not satisfied by it
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But think of all the cool things that do NOT happen here but somewhere else. It's the same case of coincidences, for example dreaming about somebody and later meeting them. You just won't remember all the times you dreamt somebody and didn't meet them. We only pay attention to exceptional cases,
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I've travelled to totality and I will say it is uniquely surreal. It really feels like you've entered a different place because the lighting is all wrong. If there was one experience that ever felt like a glimpse at *something* divine, I would vote on that for sure.
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Intelligent Design weirdos: eVeRYtHiNg iS bY dEsIGn!
Bats: our wings are the same as your hands, but with big long spindly fingers and leather attaching them together. Coulda been something better, this is what I came up with.
Humans: we still have an appendix and wisdom teeth for some reason!
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People will post sunset photos and be all “look at God’s gift!”

I’m all “it’s just sunlight refracting off air molecules in the atmosphere more because it passes through at a shallower angle and hits more during sunset.”

Yes, I am fun at parties.
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To be your annoying atheist for a moment, I find myself thinking if, for example, eclipses have the effect of promoting the conditions for intelligent life. Being able to go straight from "that's amazing" to "what a neat thing God did" can be limiting.
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Think about this shit: if aliens knew about it, eclipses would be a hot tourist destination. We'd probably even get alien scientists checking it out.
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It's only insane if you consider it in isolation. A child look likes it's grandparents. The physics of planets and stars is far more simple than genetics.
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Yeah, our moon is huge compared to the planet. Moons aren't supposed to be this big.
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yes tf they are other planets better get on our level
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As far as we know the Moon has the largest moon-to-planet ratio in the universe. It does make sense sometimes to speak of a binary Earth-Moon system.
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The Theia impact is my answer to the Fermi paradox - our tilt, composition, heat, and moon are all weird and important to biogenesis and the evolution of complexity.
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Pluto, dancing with Charon: “They AREN’T?”
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I LIKE BIG MOONS AND I CANNOT LIE!
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But, seemingly, the moon is moving away from us at 4cm per year….
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Apparently that speed has accelerated recently….
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Yup, before long, total eclipses of the sun will be a thing of the past. Not before human extinction, of course.
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Thing is when I was a kid I learned tits 6mm a year, watched a Niel D T YT a couple days ago that said a meter an a half a year. An now I read 4cm? Better recording? Math?
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No wonder people believe in supernatural stuff. It feels way too good. Plus all the other stuff on Earth that was only truly explained in the last few centuries.
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The odds of that, and us being around to see it, are literally astronomical. And that’s magnificent.
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Even more headfucking is that this has not been the case for all that long and, worse, won't carry on being the case for that much longer. Well, not that much longer in cosmology terms. 600 million years will probably see us out.
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I was googling about the moon after the last solar eclipse and stumbled across an article about how the moon will eventually become locked to the earth's rotation, and only one side of the earth will be able to see it anymore. And I was thinking about how sad it would be, and then at the end of the
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It’s just a phase we’re going through so. A lunar phase.
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So that means earlier lunar eclipses were not as cool, since the moon blocked more of the corona? But as we are getting into the final billion years of the eclipse period, we get the coolest ones, with the best views of the corona?
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The fact that they appear the same size is incredible, but to be clear, that's not required for total eclipses--all that's required is that the Moon appears at least as big as the Sun. (E.g. moon could be 3x bigger and total eclipses would still be possible, even marginally more common.)
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Yes, but then we wouldn't see the corona.

So they'd happen, but wouldn't be nearly as spectacular.
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A 99 percent eclipse is shit compared to a 100 percent eclipse. I found this out firsthand in 2017.
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Thanks to David Banks at the other place, who first alerted me to Ian Banks' reference to this face in his novel Transition, in which a character posits that if aliens exist on Earth, we'd find them watching an eclipse.
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Oh hell I just made a reference to this in someone else's quote of your first post!

Whoops!

But yeah it's very cool
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I look for aliens at every eclipse now, but I'm sure we're a Special Circumstances project so they know to lay low.
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He almost "invents" the term "rawdogging" there, too.
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Longer quote of that section available here, for the curious...

news.ycombinator.com/item?id=26263356
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See also the short story "And Come from Miles Around" by Connie Willis which has the same idea, published more than 25 years before that novel. (Collected in the book "Fire Watch")
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That's 100% someone who's seen one. I've forgotten most details, but I'll always remember the feeling. The sound.
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I adore this idea, I think about it every time this topic comes up
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Such a beautiful thought. Thank you for sharing this
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Excellent thought!
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This is wonderful, thank you for sharing
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yes, it's so fabulous! thinking about the implications for mythology is so interesting. imagine if one were visually smaller. you'd get so many stories relating them in a different way.
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I'm writing a book and in my world there are two (smaller) moons, so they get a whole lot of myths regarding them^^
It's honestly a funny thing to imagine
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I mean if the moon were closer and significantly larger than the sun the eclipse would still happen
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Yeah but it wouldn't look nearly as striking (and also there would probably be significant issues re: gravity and tidal forces in that case as well)
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Without solar eclipses, Hank Morgan, the Connecticut Yankee, might not have survived to return to Bridgeport to tell Mark Twain about his adventures in King Arthur's Court and further the cause of anti-imperialism.
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see <pinned tweet>
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It's the one thing that keeps me from being a complete atheist
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What? Chance? 🤣
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it's less shocking to me when i remember that there's probably trillions of opportunities for incredible coincidences like that to happen, and we just focus on the few instances where the coincidence actually happened
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Would a total eclipse not be possible also if the moon was bigger than it is instead of just the right size?
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I think about this a lot. It's so cool.
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Only temporarily though so these aliens should hurry up
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Combined with the rotation and orbit of the moon being such to have a light and a dark side it really is quite an amazing coincidence. Surprised religious types never point to this stuff as proof of their deities.
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that perfect 400:400 ratio feels like the universe left us an easter egg. the kind of mathematical coincidence that makes you wonder if there's a deeper pattern hiding in plain sight, or if we're just lucky to witness such symmetry.
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It's only like that for now. The moon is drifting away and eventually it will be too small to fully eclipse. That's somebody else's problem though.
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Ah yes must be that meddlesome God on a cloud ; designer extraordinaire
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Add to that the fluke that the moon is slowly moving away from the planet, and that millions and millions of years ago it would’ve looked bigger. So add in the fluke of us existing at a point in time where we can appreciate total eclipse.
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At present!
A reminder to enjoy it while you still can - in a couple of million years it won't be.
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Combine that with the fact that the moon is slowly moving away from Earth means that we are at just the right time to set it on a cosmic time scale.
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Without those specific numbers, it's actually guaranteed, providing Earth got a moon at all (and it didn't originate too far out). At some time, that perfect relative size would definitely occur. It's just a matter of whether it happens when there are people around to see it.
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And, because the moon is slowly spiraling away from the earth, it's only like that for a cosmically "brief" moment that just happens to coincide with the presence of human observers.
Long ago the moon was too large in the sky for a visible corona; in the future it will appear too small for totality
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Moon’s angular diameter just has to be larger than that of sun. They don’t have to be equal. Makes it less coincidental. All of the gas giant outer planets, plus Pluto, can have total solar eclipses from at least one moon.

Still cool though.
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This very similar to the idea that the tallest mountains on earth also seem to be at the height at which humans can no longer breathe.
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It may well not be a fluke that we have a big moon - strong theory it stops the earth's axis wobbling so much there'd be no stable climate.
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Well the moon could be any size bigger or closer too, right?
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If you start with the idea that the Moon formed after a collision between proto-Earth, and a Mars sized asteroid. Continue with the idea that the Moon is slowing the spin of the Earth, and using that energy to increase its orbital distance. Then it becomes inevitable that it would at some point...
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pass through that space where it and the Sun have equal angular size. That only makes it cooler in my opinion.
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Only for right now, too. At one point the moon was too close for it to work, and at some point it'll be too far away, but for right now we get total eclipses. Pretty neat stuff.
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the moment when all the shadows make crescents genuinely felt like i was understanding something about the world that i wasnt supposed to the last total eclipse i saw
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Yeah this fucks me up from time to time. Like I don't think we were created here specifically by God. But.
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The lesser discussed theory is that this fact is anthropic: species develop consciousness in planetary scenarios with certain mathy characteristics.

"It is God who made the sun radiant, and the moon a light, and determined phases for it—that you may know the number of years and to calculate"
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So there might be other planets supporting organic life, but where the skyscape is so boring none of it could be bothered to evolve the consciousness needed to appreciate it.
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The precise coincidental alignment in space and time of our solar eclipse is what I think of when I want to believe in the human sense of miracle - our need for it - without any belief in a God.
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Imagine aliens have visited Earth many times. But they just want to see the moon thing and don't care about humans at all.
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All the alien abductions are just asshole tourists harassing the locals.
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Not to mention the amount of poetry that wouldn’t work nearly as well.
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