When and how did humans first realize that it was darker/lighter on other parts of earth at the same time?

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I get how time zones were established, and I get how people knew the earth was round thousands of years ago, so I assume that it was hypothesized that some areas of earth were darker/lighter than others at the same time. I feel like it was kind of unprovable though due to limitation. At what point did we actually confirm that it was indeed night time somewhere else when it was daytime on the opposite side of the world? And how was the found out?

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Anonymous 0 Comments

Even before it was widely accepted that the Earth is round, people knew that the Sun was the source of light. They could also observe the lunar day on the Moon and see how it was never truly fully illuminated. So if you know there is a single light source, you know the Earth is round and you also have a visual example of how a round body is illuminated by a single light source, the rest kinda just falls into place.

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