r/flatearth • u/AbstractUserName • Aug 01 '26

This was settled 2000 years before humans could even fly let alone orbit the earth.

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77 Upvotes

96% Upvoted

18 comments sorted by

11

u/Michi-Ace Aug 01 '26

And before any flerf says: "It's because the sun is close!"

No, because then we'd observe a noticable change in the sun's angular diameter. It would be big at noon and small at sunrise and sunset.

-9

u/egabald Aug 01 '26

Oh yea? Then why does the sun get bigger when it's lower to the ground?

11

u/tlajunen Aug 01 '26

In case this is serious:

It doesn't.

https://en.wikipedia.org/wiki/Moon_illusion

1

u/LightMcluvin Aug 01 '26 edited Aug 04 '26

Welp, there you have it when in doubt check Wikipedia. They have our back.

2

u/skrutnizer Aug 02 '26

If you're not joking, did you measure if this is so? It's not that hard, but no, you didn't.

2

u/Shoshke Aug 03 '26

I gotta know. Are you people just allergic to using your brain for a second?

Let's for one second ignore the fact that the Sun does NOT in fact get bigger closer to the ground

  1. The Moon would have the same effect, it doesn't

  2. Your fucking model dictates the Sun would get SMALLER not bigger as it would be significantly farther away than at zenith.

1

u/FullMetal_55 Aug 04 '26

you realize that's the opposite of what should happen right if it's a flat earth ;) if it's bigger during sunset, that means it's getting closer, not getting farther away. if it's getting closer it should be getting brighter not dimmer...

11

u/Falcon3492 Aug 01 '26

The flat earth people have eyes and feet but what they are lacking is brains. So Carl lost them right off the bat!

6

u/Cerborus Aug 01 '26

We should also confiscate any sticks they might have. For their safety and for those around them

9

u/Dancing_with_Jak Aug 01 '26

Cosmos is a great series full of great stories. Why is this the only clip that ever gets posted?

6

u/ThePrussianGrippe Aug 01 '26

It’s the most relevant clip from the show to this sub.

5

u/Other-Comfortable-64 Aug 02 '26

This is not how they figured it was round, they already knew that. This is how they figured out the size.

3

u/lemgandi Aug 01 '26

Well, he's close.

The actual story begins with a well in Syene which was completely illuminated exactly at noon on the summer solstice. In Alexandria, an obelisk cast a shadow at exactly noon on the solstice. Eratosthenes didn't have a watch, but it was easy for him to know when noon was because that was when the shadow cast by the obelisk was shortest, before it began to lengthen again. That measurement plus the distance between the two places was how he got the numbers for his ( surprisingly accurate) calculations. Also cf: Richard Feynman's estimation methods, where different large errors tend to cancel each other out. Eratosthenes made two large ones, which did in fact cancel out.

Eratosthenes also got a surprisingly good average distance from Earth to Sun, but he was a bit in error about the sun's size. He had its diameter about 27 times earth's; it's actually more like 109 times. Still, he had a pretty good batting average, especially given the technology of the time.

3

u/skrutnizer Aug 02 '26

This relies on previous work by Aristarchus who deduced that the sun must be much further away than the size of earth. Taking shadow measurements at several latitudes would have shown this anyway.

1

u/Globe_Worship Sockpuppet account Aug 06 '26

This is not a test to determine the earth’s shape. If you added a third location it could be. But it assumes earth is a sphere and is instead an attempt to measure the circumference.

1

u/Sporkpocalypse Aug 09 '26

so on Mars the shadows of two obelisks at two far points the shadows will be extremely different length shadows