Great clear breakdown of how we see and what we see at distances like the horizon.. Shows that the sun does not set below an non-existent earth curve but recedes beyond our abiltiy to see it, our angular resolution of .02 is exceeded. see entire video here at Curious Life https://www.youtube.com/watch?v=o6clRx5Ftyo
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https://www.youtube.com/watch?v=3fILF6ZKnOQ