Which scientist proposed the three laws of motion published in 1687?

Isaac Newton proposed the three laws of motion published in 1687. They appeared in his landmark book Philosophiæ Naturalis Principia Mathematica, usually called the Principia, which established the foundations of classical mechanics.

The first law describes inertia: an object remains at rest or moves at constant velocity unless a net external force acts on it. The second connects force, mass, and acceleration, commonly written as F=ma. The third states that interacting bodies exert equal and opposite forces on each other.

Newton built on earlier work by Galileo Galilei, Johannes Kepler, and René Descartes. His laws helped explain both ordinary motion on Earth and the movements of planets when combined with his law of universal gravitation.

A common mix-up is crediting Galileo or Kepler with the three laws. They made crucial contributions to the study of motion and astronomy, but Newton was the scientist who formulated the three-law system and published it in 1687.