What specific solar observation was made in Syene (modern Aswan) at noon on the summer solstice?

Answer

Vertical sticks cast no shadow

In Syene, at noon on the summer solstice, the Sun was directly overhead, meaning vertical sticks cast no shadow and sunlight reached the bottom of deep wells.

What specific solar observation was made in Syene (modern Aswan) at noon on the summer solstice?
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