Background
He made important pioneer contributions on harmonic analysis and tide-prediction. This included tidal friction in reference to binary-star evolution as well as to the moon and the earth. Darwin traced in theory the past and future history of the earth-moon system, showing the probable changes in months and days and the possible birth of the moon from a parent earth. His book, The Tides and Kindred Phenomena in the Solar System (1898), is a classic. He also made important researches on the problem of three bodies and on periodic orbits. Darwin died at Cambridge, Dec. 7, 1912.