Which of the following achievements is Johannes Kepler best known for?

Johannes Kepler is best known for first stating the laws of planetary motion, which fundamentally changed the understanding of celestial movements. His work in the early 17th century built upon the observations made by Tycho Brahe and resulted in three critical laws that describe the orbits of planets around the sun.

The first law, known as the Law of Ellipses, states that planets move in elliptical orbits with the sun at one focus. The second law, or the Law of Equal Areas, explains that a line segment joining a planet and the sun sweeps out equal areas during equal intervals of time, indicating that planets move faster when they are closer to the sun. The third law gives a mathematical relationship between the time a planet takes to orbit the sun and its average distance from the sun.

These laws not only advanced the field of astronomy significantly but also provided a foundation for the later work of physicists like Isaac Newton, who would incorporate Kepler's insights into his own theories of gravity. Kepler's meticulous observations and calculations thus had a lasting impact on both science and our understanding of the universe.