Menelaus

of Alexandria

Spherical geometry’s ancient MVP. Menelaus of Alexandria (fl. early 2nd century CE) made geometry go three-dimensional with his Sphaerica, laying the foundations for spherical trigonometry — essential for astronomy, navigation, and pretending the Earth is flat (just kidding). He saw the stars not as decoration, but as puzzles to be solved with arcs and angles. If Hipparchus charted the sky, Menelaus gave it structure. Without him, mapping the heavens would be a shot in the dark.