Isaac Newton lived during the scientific revolution of the 17th century. While men like Kepler, Galileo, and Descartes had shaped a new view of nature, Newton organized and expanded all the scientific knowledge available at the time. Galileo died the year Newton was born. Galileo had already established: the sun was at the center of the universe, other planets had moons (Jupiter), and the sun was not 100% luminous as spots were evident. Galileo's universe model was heliocentric like Copernicus' model before him. Johannes Kepler's work was based on the work of Tycho Brahe. Kepler's ideas were revolutionary. He believed the planets traveled in an elliptical or oval pattern. Kepler devised three laws that provide the first kinematic description of orbits: (1) The law of elliptical orbits, (2) The law of equal areas; and, (3) The law of harmonics:
Law 1: Planets move in an elliptical orbit with the sun at once focus,
Law 2: A line connecting the sun and a planet (radius vector) sweeps out equal areas in equal times; and,
Law 3: The square of a planet's orbital period is proportional to its mean distance from the sun cubed.
Newton believed like others before him that the universe was heliocentric. He expanded on Galileo's work to provide a better explanation for the relationship between energy and motion. Where Kepler developed a kinematic description of orbits, Newton would refine Kepler's theories and develo
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