Statement that any particle of matter in the universe attracts any other with a force (F) that is proportional to the product of their masses (m 1 and m 2 ) and inversely proportional to the square of the distance (R) between them.
In symbols: F = G (m 1 m 2 )/ R 2 , where G is the gravitational constant. Isaac Newton put forth the law in 1687 and used it to explain the observed motions of the planets and their moons, which had been reduced to mathematical form by Johannes Kepler early in the 17th century.