Final answer:
Johannes Kepler is the one who enforced the three laws of planetary motion and established that orbits are elliptical, not Isaac Newton, Galileo Galilei, or Albert Einstein.
Step-by-step explanation:
The person who enforced the three laws of planetary motion and established that orbits are elliptical was Johannes Kepler. Kepler's first law states that the orbits of the planets are ellipses with the Sun at one focus, contradicting the previously held belief that orbits were perfect circles. Kepler formulated these laws by meticulously analyzing the exceptionally precise data collected by Tycho Brahe. These laws include: (1) Planetary orbits are ellipses with the Sun at one focus; (2) A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time; (3) The square of the orbital period (P) of a planet is proportional to the cube of the semi-major axis (a) of its orbit.While Isaac Newton did not enforce the laws of planetary motion, his work indeed complemented Kepler's laws. Using these laws and observations, Newton developed the universal law of gravitation, which provided the forceful explanation for these motions. Galileo Galilea's mathematical approach to the universe and his observations also supported the heliocentric model, while Albert Einstein's theory of general relativity refined our understanding of gravitation. However, it was specifically Kepler who was responsible for the formulation and enforcement of the three laws of planetary motion.