Johannes Kepler

Renaissance astronomer who revolutionized celestial mechanics with his laws of planetary motion.

Johannes Kepler (1571–1630), a German mathematician and astronomer, transformed humanity's understanding of the cosmos. His three laws of planetary motion dismantled the ancient belief in circular orbits, proving that planets move in ellipses with the Sun at one focus. This breakthrough supported the heliocentric model proposed by Copernicus and paved the way for Newton's law of gravitation.

Kepler's first law (Law of Ellipses) and second law (Law of Equal Areas) appeared in his 1609 work Astronomia Nova. His third law, relating orbital periods to distances, was published in Harmonices Mundi (1619). These discoveries emerged from meticulous analysis of Tycho Brahe's observational data, particularly on Mars' orbit.

Beyond astronomy, Kepler contributed to optics, inventing an improved telescope design and explaining how the human eye focuses light. His Somnium (1634), a fictional lunar journey, is considered one of the earliest works of science fiction.

Despite personal hardships—including his mother's trial for witchcraft—Kepler's blend of mathematical rigor and philosophical curiosity epitomized the Scientific Revolution. His laws remain cornerstones of astrophysics, enabling space exploration and modern cosmology.