Hipparchus
of Nicaea

The astronomer who brought the heavens to heel. Hipparchus of Nicaea (c. 190–120 BCE) invented trigonometry, discovered the precession of the equinoxes, and compiled star charts so precise, Ptolemy basically just updated them. He compared observations across centuries and wasn’t afraid to call out older sources when they got it wrong. Quiet, calculating, and endlessly curious, Hipparchus turned astronomy into a science of data — centuries before telescopes. The cosmos got organized, and it never looked the same again.