<P> In 1687 , English mathematician Sir Isaac Newton published Principia , which hypothesizes the inverse - square law of universal gravitation . In his own words , `` I deduced that the forces which keep the planets in their orbs must be reciprocally as the squares of their distances from the centers about which they revolve ; and thereby compared the force requisite to keep the Moon in her orb with the force of gravity at the surface of the Earth ; and found them answer pretty nearly . '' </P>
<P> In 1687 , English mathematician Sir Isaac Newton published Principia , which hypothesizes the inverse - square law of universal gravitation . In his own words , `` I deduced that the forces which keep the planets in their orbs must be reciprocally as the squares of their distances from the centers about which they revolve ; and thereby compared the force requisite to keep the Moon in her orb with the force of gravity at the surface of the Earth ; and found them answer pretty nearly . '' </P>
who came up with the theory of gravity
who came up with the theory of gravity
Sir Isaac Newton
Sir Isaac Newton