Johannes Kepler and His Scientific Contributions

By Katelyn Cooper

Apprenticeship

• Lived from 1571-1630• German moved to Prague to become Brahe’s

apprentice• Brahe told him to watch the orbit of Mars, so

Brahe could continue with his theory on the solar system

• He kept him occupied with the orbit of Mars because Brahe didn’t trust Kepler, he thought one day, Kepler would eclipse him as the premier astronomer of his time.

Kepler’s Theory

• Kepler believed in the Copernican System, which placed the sun directly in the center of the planets orbits.

• Kepler realized Aristotle was wrong when he said that the orbits of planets were circular. In the system Copernican assumed they were circular also.

• Kepler proved that the theory was not wrong but the shape of the orbit was, the orbits were flattened circles, also known as ellipses.

First Law of Planetary Motion

• Kepler’s first law stated that the sun was not the center of planet’s orbits but at one focus.

• Which means the sun’s distance is constantly changing.

Equal Area Law of Planetary Motion

• The line joining the planet to the Sun sweeps out equal areas in equal times as the planet travels around the ellipse.

• The planet moves faster when it is closer to the sun.

• 2 parts: the perihelion and the aphelion

Harmonic Law of Planetary Motion

• The ratio of the squares of the revolutionary periods for two planets is equal to the ratio of the cubes of their semimajor axes.

• Kepler's Third Law implies that the period for a planet to orbit the Sun increases rapidly with the radius of its orbit.

• P represents the planet’s period of revolution

• R represents the planets axis’

Interactive Sites

• Kepler's First Law

• Simulation of Orbit

Bibliography

• "Johannes Kepler: the Laws of Planetary Motion." Johannes Kepler: the Laws of Planetary Motion. 15 May 2006 <http://csep10.phys.utk.edu/astr161/lect/history/kepler.html>.

• Spaulding, Nancy E. Earth Science. Dallas: McDougal Littell, 1999. 405-406.

• Porter, Roy, and Marilyn Ogilvie. Dictionary of Scientists. 3rd ed. Vol. 1. Great Brittain: Helican, 2000. 554-557.