## 0085 – Ptolemy – bio

**Claudius Ptolemaeus** was born in Egypt around 85 as a Roman citizen. He was a mathematician, astronomer and geographer. He is famous for a series of books:

- Harmonics – on musical theory
- Optics – properties of light, including reflection, refraction and color
- Geography – used a coordinate grid system
- Tetrabiblos (four books) – on astrology
- Planetary Hypothesis – a geocentric model that described the planets as moving in nested orbital shells
- Syntaxis (aka Amagest) – mathematical astronomy, included a catalog of stars and constellations

PREREQUISITE:

Hipparchus

Pythagoras

SUBSEQUENT:

**1473 – Copernicus**

Kepler

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