Historical Astronomers in Context – Johannes Kepler

Portrait of Kepler from Wikipedia

Johannes Kepler. (Dec.27.1571 – Nov.15.1630)

He was important to astronomy for his revolutionary discovery of laws of planetary motion, and his books Astronomia novaHarmonices Mundi, and Epitome Astronomiae Copernicanae. His laws of planetary motion describe how planets orbit around the Sun and the relationship between their period and their orbit length. His works contribute to Newton’s theory of gravity too.

Contemporary events:

In 1614, John Napier discovers logarithms. Logarithms is a new function which extended the world of math and analysis beyond the scope of algebraic methods. The method of logarithms was discovered and published first by John Napier in 1614 in his book called Mirifici Logarithmorum Canonis Descriptio(Description of the Wonderful Rule of Logarithms).

In 1610, Galileo sees the moons of Jupiter (Galilean moons) through his telescope. Galileo’s discovery marked the importance of telescope as a tool for astronomers as telescope allowed him to find objects in the sky that could not be detected by naked eye. More importantly, the discovery of moons of Jupiter disproves the Ptolemaic world system, which held that everything has to orbit around the Earth. 

Contemporary person:

Jan Baptist van Helmont. (Jan.12.1580 – Dec.30.1644)

Portrait of J.B van Helmont. Picture from Wikipedia.

He was a Flemish chemist, physiologist, and physician. He is sometimes considered to be “the founder of pneumatic chemistry”. Van Helmont is important to science development and chemistry for his discovery of CO2 and ideas on spontaneous generation. He was one of the first people realizing there are gases different from normal air in our atmosphere and furthermore he introduced the word “gas” (from the Greek word chaos) into the vocabulary of science.


It’s very interesting to see that Galileo Galilei has lived entire life of Kepler and they are both huge astronomical figures to today’s science and astronomy. Also 16thcentury and 17thcentury was a huge revolutionary period in science in which a lot of great scientists are born and discoveries are made, just like Kepler’s laws of planetary motion, Newton’s law of gravity and discovery of CO2 and the word “gas”. All of these histories make me feel that the history of science is step-by-step with discoveries made based on achievements of our predecessors. And our scientific discoveries today will become the bricks for our future science development.