Americanmathematician and astronomer. Inspired by the work of L. Euler, he developed advanced mathematical methods for tackling problems in dynamical astronomy. His first major work was an application of the three-body problem: the orbits of Jupiter and Saturn and the perturbations exerted by these planets on the Moon. In his study of the Moon's motion he introduced a differential equation now known as Hill's equation.
Subjects: Astronomy and Astrophysics.