MATHEMATICIAN, ASTRONOMER

Life
Cited by Diodorus Siculus and by Proclus in his "Commentary on Euclid", Oenopides travelled widely through Egypt and acquired considerable skill in astronomy. His work focused on studies of the lunar and solar years. The discoveries he made were engraved on a bronze tablet which he offered to Olympia.


Work
His work also included:

The first geometric constructions with ruler and compasses (e.g. "Perpendicular to a line from a point that is not on that line", "Construction on a given straight line of an angle equal to a given angle).

The discovery of the inclination of the ecliptic.

The introduction into Greece the "Great Year" of 59 years. Oenopides accepted a year of 365 days and a month of 291/2 days. 59 is the largest whole number of years that contains an exact number of lunar months (730). Since 730 lunar months correspond to 21,557 days, each year in the Great Year would have 365.373 days, or a little less than 365 days and 9 hours.