feynmanlectures.caltech.edu

VBWL4 TIL Claudius Ptolemy made a list of the angle in water for each number of different angle in air, as recorded on a table from 140 AD. But it was not until 1621 when Willebrord Snell found the rule connecting the two angles: sinθi=nsinθr
Zp5Za TIL Newton tested the theory of gravitation involving the moon and Earth but found a discrepancy so large that he did not publish it. Six years later, a new measurement of the size of the Earth and distance of the moon came out and Newton recalculated again to show his theory worked
M7Y77 TIL Two chemical elements were discovered on a star before they were discovered on the earth. Helium was discovered on the sun and technetium was discovered in certain cool stars