(Johann Kepler, 1571-1630): (1) That the planets describe ellipses, and that the centre of the sun is in one of the foci. (2) That every planet so moves that the line drawn from it to the sun describes equal areas in equal times. (3) That the squares of the times of the planetary revolutions are as the cubes of their mean distances from the sun.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
More on Kepler's Laws from Fact Monster: