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SmorgasConfigurator t1_ize24qx wrote

One thing that in principle can be different is the crater patterning. However, it seems unlikely that has changed in any meaningful degree in human history.

Certainly not all craters have been dated, but a decent number has. You can access a crater Excel sheet on this page. I shortlist two that stand out:

  • The crater named Giordano Bruno has an interesting history. In 1178 there is a well-documented event on the moon where "fire, hot coals and sparks" burst from the moon. It has been thought this was when an impact caused the creation of this crater. That would have been a change to the lunar surface that a keen observer would have noted. So at least Ceasar would have looked at a different moon than today. However, this theory has been doubted since there is no record of an associated meteor storm on Earth, as would have been expected. So this is at least a young crater, but probably not as young as 1178.
  • The crater named Eimmart A is noted in the database as "very young". It is a small crater, however (~7 km diameter), and when the lunar people say "very young", they mean it is "probably less than 100 million years ago". So sure, maybe it might have formed early during the human era. Still, not that likely.

From what I can tell, a major crater formation that would change the appearance of the moon viewed with eyes would generate a great deal of meteors on Earth, like when comet debris hit Earth. I do not know enough obscure history, but if a major crater formed while there were literate humans on Earth, then maybe they would have recorded that as some great mystical event.

So in short, my best guess is that major crater formation that would alter the view of the moon during human civilization is unlikely, but possible.

My guess is that light pollution from cities are a bigger difference in how the moon appears to us and to Ceasar.

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ayebrade69 OP t1_ize2ovz wrote

This was exactly the type of answer/discussion I was looking for. Fascinating. Thank you!

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Significant_Sign t1_ize5xkk wrote

Thanks for all that! The surface appearance is where my mind went to immediately, but I know nothing about this stuff. Glad to see something besides the distance & apparent size.

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Right_Two_5737 t1_ize5dxb wrote

I can't see any craters on the moon with the naked eye. Can anyone else? Would there be any naked-eye differences apart from light pollution?

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SmorgasConfigurator t1_ize6x7r wrote

The question in OP allows for some interpretation. Even if there was a crater formed in 1178, I doubt Ceasar would be shocked by the appearance of the present-day moon. So I am trying to think of what could be recognized as different by a keen observer (yes, fuzzy definitions, but history is full of dudes that stare into the sky and see things, so imagine one of those characters).

But you can see some "texture" on the moon surface. Especially when the moon is about one week after new moon, it is not yet that bright that you only see a bright disk in the night sky. This assumes you are in a relatively dark place to begin with, so far from a city, and that the sky is clear. Even then, the craters have to be pretty large to be observable as pattern, hence the many small craters that form are irrelevant even to the keen observer I imagined.

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BrainOnLoan t1_izfj2lx wrote

Some of the big ones can be seen with the naked eye, mostly as white spots, but those surely haven't changed recently.

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stayalive2020 t1_izdx66w wrote

The moon is slowly moving farther away from the earth. But for humans to notice you'd have to span out 10,000 plus years at a time. NASA claims its about 3.8 centimeters a year. Definitely not noticeable in one's lifetime.

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dirschau t1_izdzzcr wrote

You wouldn't notice it over the span of the entire human history. Even per 10000 years, that's less than half a kilometer. The moon's orbit varies by 40 thousand kilometers between perigee and apogee every two weeks.

You might start noticing movement if you make frames of a million year's change, and even then after a minute of that video (so about the dinosaur extinction) it would have shifted by a few thousand kilometers, less than the perigee-apogee difference.

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stayalive2020 t1_ize06av wrote

You should have answered first lol, thanks for the info!

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dirschau t1_ize4div wrote

No worries, it's just funny when you learn that "oh, it's moving away almost 4 centimetres a year, that's a clearly measurable distance. Mountains grow that fast" but then realise you're talking about literal astronomical distances, lol

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[deleted] t1_izdxtua wrote

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[deleted] t1_izdzafn wrote

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series_hybrid t1_izesvel wrote

I think the biggest change in perception might be when Galileo observed it through a telescope.

The way I recall the story is that a glass blower noticed if water was in a round goblet, then anything behind it was magnified. He experimented, and made a low-power telescope, which was eventually brought to the attention of Galileo.

Galileo showed this the the leaders of the town, and showed how it could be taken to a tower to see a ship that is on the horizon, much sooner than could be seen with the naked eye.

The city paid a contract to start making these portable telescopes, and with the profits, he funded the making of machines that could grind and polish much larger lenses.

With a larger telescope, he got good view of the phases of Venus, a good view of Mars, Jupiter, and Saturn, along with the four largest moons of Jupiter. And of course a close-up of our moon, allowing him to make detailed drawings of the craters.

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risingstanding t1_izfauqo wrote

I'm interested in a related question: how did people's perception of what the moon even is, change across time? I'm aware of the idea in cartoons and such that people used to think it was cheese or whatever. But anyway, what kind of info is there on all this? Now, when I look up at the moon, I think of it as a place, I think of it as rock...what did people think before they knew about planets, and then being round? When did people think of the moon as a place you could go?

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Maddog_95 t1_izh95rm wrote

One time I looked up at the moon and I swear it looked like I was in a dark container and there was a tiny hole to a bright light. Made me wonder what other things people perceived or stories they came up with!

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yaminokaabii t1_izhga17 wrote

I once saw an image depicting different cultures' perspectives on the heavenly bodies that would've answered you wonderfully. One was that the sun, moon, and stars were big balls moving around a planar Earth... another that the sky was a dome and they were little holes cut out to reveal the infinite fire beyond.

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Snowy_Eagle t1_izgrcjl wrote

This is exactly where my mind went too. The visual data your eye is receiving might be more or less the same (especially if you are out in a place minus the light pollution). But the way you are perceiving it could still be completely different...

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Scott_Abrams t1_izffs2a wrote

Human history is pretty short, beyond advances in technology (ex. telescopes, corrective lenses, etc.) and light pollution, I don't think there are any noticeable changes. The moon's orbit is pretty stable, even if it's gradually slowing down the rotation of the Earth and moving away at like, 4 cm a year. Maybe there are more footprints and craters on the moon's surface? But to the naked eye, I honestly don't think there's much of a difference. A few thousand years is nothing on a cosmic level.

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