Anaxagoras

Pre-Socratic Greek philosopher whose work profoundly influenced astronomy, mathematics, and the development of scientific thought

c. 500 – 428 BCE

Astronomical Contributions

Lunar Light and Eclipses

Anaxagoras correctly explained that the Moon does not produce its own light but reflects the light of the Sun. This insight allowed him to provide the first correct explanations for solar and lunar eclipses.

Nature of Celestial Bodies

He proposed that the Sun was a mass of red-hot metal and that the Moon was an earthy body with mountains and valleys. He also suggested that stars were fiery stones, challenging the traditional belief that celestial bodies were gods.

Cosmology and Meteorites

Anaxagoras proposed that the Earth was flat and floated on air. He theorized that meteorites were rocks torn from the Earth and ignited by rapid rotation. He is credited with predicting the fall of a meteorite in 467 BCE.

Mathematical Contributions

Squaring the Circle

Anaxagoras was among the first to attempt the problem of squaring the circle (constructing a square with the same area as a given circle using only a compass and straightedge). He worked on this problem while in prison.

Geometry and Perspective

According to the Roman architect Vitruvius, Anaxagoras wrote a treatise on perspective in art, explaining how to create the illusion of depth in stage scenes. Although this work hasn't survived, it suggests he applied geometric principles to practical problems.

Philosophical Foundations

Anaxagoras introduced the concept of Nous (Mind or Intellect) as an ordering force that initiated the cosmos. This idea was foundational for later scientific thought, as it proposed a rational basis for cosmic order.

"The Sun is a mass of red-hot metal, larger than the Peloponnese."

"The Moon is an earthy body with mountains and valleys."

Key Contributions Summary

Astronomy

Correct explanation of eclipses; Moon reflects sunlight; Sun as fiery mass

Mathematics

Early work on squaring the circle; treatise on perspective

Cosmology

"Theory of Nous (Cosmic Mind); everything-in-everything; meteorite predictions

Legacy

Pioneered scientific rationality; tried for impiety; influenced Athenian philosophy

Anaxagoras' work exemplifies the shift from mythological to rational explanations of the cosmos.

His astronomical and mathematical ideas were groundbreaking for their time and remain a testament to the early spirit of scientific inquiry.