World History Encyclopedia
World History Encyclopedia: Greek Astronomy
Looks at the history of Greek astronomy from the 4th century BC on, and the major figures who contributed ideas. Includes a timeline of Greek science.
Cornell University
Cornell University: Astronomy: Aristarchus
This site from Cornell University provides a discussion of how Aristarchus arrived at his conclusions of the distance from the Earth to the Sun and Moon. Also has his methods for determining the size of the Moon and the Sun.