This web page provides information about Newton’s theory of universal gravitation and some discussion of the history of Newton’s work on this topic. Featured are a calculation for the orbital period of the moon and the formula for the force of gravity. Several links to source material on Newton and his work as well as a lesson plan for instructors are also available. This is part of an extensive web site, “”From Stargazers to Starships””, that uses space exploration and space science to introduce topics in physics and astronomy. Translations in Spanish and French are available.