Hypsicles

Hypsicles was an ancient Greek mathematician and astronomer who lived in the 2nd century BCE. He is primarily known for his work on the calculation of astronomical cycles and for his geometric theorems.

One of Hypsicles' most significant contributions is found in his work "On the Ascensions of the Stars" (De Sphaera). In this treatise, he discussed the concept of the ecliptic and how different zodiacal constellations rise at different times. He also explored the idea of measuring the stars' positions by their ascension, a method that influenced later astronomical calculations. This work also contains an early mention of the concept of a tropal year, which is the time it takes for the sun to return to the same point in the sky relative to the solstices or equinoxes.

Hypsicles is also credited with a theorem concerning regular polygons inscribed in a circle. While often attributed to Euclid, some scholars believe Hypsicles may have independently discovered or elaborated upon this geometric principle. His mathematical work demonstrates a sophisticated understanding of geometry and its application to astronomical problems, making him a notable figure in the history of ancient science.