Oenopides - The Blazing Sun in Greek Science

Oenopides of Chios was a Greek astronomer, mathematician and geometer, who was born on Chios shortly after the year 500 / 490 BC on the island of Chios, and died about 420 BC. In the time around 450 BC, he was living in Athens, with revolutionary discoveries in both astronomy and geometry.

 

It is likely that Oenopides of Chios was the mentor for the famous mathematician Hippocrates of Chios, who in his field gained a much wider recognition for his work. Oenopides, however, was more active in areas of astronomy and geometry, in which he contributed greatly with his research and theories.

One of these in the field of astronomy was his determination of the angle between the plane of the celestial equator and the zodiac (not in connection with the horoscope, but the yearly path of the sun in the sky). The result of 24° was a close to the actual inclination of the earth axis, which today is known to be 23.4°. Oenopides' measurement, however, remained the standard value for two centuries, until Eratosthenes determined a more accurate value. His relatively accurate definition of the solar year with 365 22/59 days and the lunar month with 29,53 days is still in use today.

Another of Oenopides' accomplishments was the determination of the value of the Great Year, a complex topic mostly interesting for astronomers and esoterics. The scientific definition of the Great Year is “the shortest interval of time that is equal to both the integer number of years and the integer number of months. As the relative positions of the sun and moon repeat themselves after each Great Year, this offers a means to predict solar and lunar eclipses. In actual practice this is only approximately true, because the ratio of the length of the year and that of the month does not exactly match any simple mathematical fraction, and because in addition the lunar orbit varies continuously.”

Oenopides assumed the Great Year to be every 59 years, equal to 730 months (before him the Great Year was measured in solar years, which means 99 months). Since he measured with 59 sidereal years (which is 21550.1 days), his approach was nearly accurate. In 730 synodical months, however, the amount would be 21557.3 days, which results in a difference of seven days. Despite these and other deviations (like the lunar orbit etc.) his definition of 59 years had the advantage that it was corresponding closely with the integer number of orbital revolutions of several planets around the sun, or in plain terms: Every Great Year the planets return to their relative positions. Shortly after Oenopides (in 432 BC), Meton and Euctemon determined a more accurate value of 18 years (or 223 months), which is called the Saros period. His research, however, was useful in another way, namely by predicting sun eclipses.

In the area of Geometry, Oenopides' innovations are more based on theoretical procedures and the improvement of certain methods. For example, he endorsed the limitation in plane geometry to work with simple tools like angles and straightedges. He also introduced the distinction between 'theorems' and 'problems', the theorem being a theoretical building block to be used as the foundation of further theories, and the problem solely being an isolated exercise without further follow-up or importance.

It is also said that Oenopides had given the explanation for the flooding of the Nile in Egypt each summer due to the different water temperatures between the upper water and the one at the bottom of the river. There is also information considering that Oenopides was of the opinion that the sun formerly moved along the Milky Way, until it was frightened by a mystical creature (Thyestes) and moved to the zodiac instead. He also considered the universe being a living organism, with God or the Divine being its soul, and fire and air being the first principles of the universe.

We have 2565 guests and no members online

Loading ...