
Johannes Kepler was a German astronomer and mathematician who lived from December the 27th 1571 to November the 15th 1630.

Kepler played a key role in the scientific revolution that occurred in the 17th century, contributing a number of scientific breakthroughs including his famous laws of planetary motion.

The three laws of planetary motion devised by Kepler are:
1. The orbit of every planet is an ellipse with the sun at a focus.
2. A line joining a planet and the sun sweeps out equal areas during equal intervals of time.
3. The square of the orbital period of a planet is directly proportional to the cube of the semimajor axis of its orbit.

Kepler was interested in astronomy from an early age, this interest was further piqued when he witnessed both a comet in 1577 as well as a lunar eclipse in 1580.

Kepler attended the University of Tübingen where he studied philosophy, excelled in mathematics, further developed his remarkable astronomy skills and even found time to create horoscopes for other students.

Kepler achieved much of his work around the same time as another famous astronomer, Galileo Galilei. The two often had disagreeing opinions but their concurrent work helped spur physics, philosophy and astronomy forward rapidly to a new level of understanding.

Kepler’s work on planetary motion helped Isaac Newton later devise his own theory of universal gravitation.

Some of Kepler’s famous work includes: Mysterium cosmographicum (The Sacred Mystery of the Cosmos 1596), Astronomia nova (New Astronomy  1609), Harmonice Mundi (Harmony of the Worlds  1619) and Epitome astronomiae Copernicanae (Epitome of Copernican Astronomy  published between 1618 and 1621).

NASA honored Kepler by naming a mission after him. Launched on March 6 2009, the Kepler Mission involves a hightech space telescope that will search for other Earthlike planets.

Famous Johannes Kepler quotes include: “Nature uses as little as possible of anything.”

“I much prefer the sharpest criticism of a single intelligent man to the thoughtless approval of the masses.”

“I used to measure the heavens, now I measure the shadows of Earth.”

“Geometry has two great treasures; one is the Theorem of Pythagoras; the other, the division of a line into extreme and mean ratio. The first we may compare to a measure of gold; the second we may name a precious jewel.”