Diagram of a solar eclipse in Kepler's book 'Ad Vitellionem paralipomena, quibus astronomiae pars optica traditur'.
Johannes Kepler (1571 to 1630) was an astronomer and astrologer from Germany. He studied divinity but discovered that he had an exceptional understanding of mathematics.
Kepler was an assistant to the Danish astronomer Tycho Brahe in Prague until 1601. His job was to make nightly observations of the movement of Mars around the sun and enter its positions into tables. He then used these tables for mathematical calculations.
In 1604, Kepler published his book 'Astronomiae pars optica' (Latin for "The optical part of astronomy"). In this book, Kepler explained how he uses optics to understand his observations of astronomical bodies, such as planets, moons and stars. Combining these discoveries with the tables of observations, Kepler was able to explain various astronomical events. His discoveries about reflection and refraction, for example, shed light on how eclipses of the sun and moon occur.
In 1609 and 1619 Kepler published two other books. In these he formulated and explained his three laws of planetary motion, for which he is now best known.
[Library reference: Cb.1/1.47]
