The Solar System online course is maintained by the Department of Physics & Astronomy at the University of Tennessee. The twenty two chapters cover everything from time and scale in the universe, development of modern...

An algebra-based overview of elementary and pre-telescope astronomy. Topics covered include sundials, seasons, calendars, precession, shape and rotation of Earth, Greek astronomy, the path to heliocentric theory and...

A collection of some 25,000 historical photographs, slides, lithographs, engravings, and other visual materials, focusing on American physicists and astronomers of the twentieth century, but including many scientists in...

In this activity students are asked to interpret a graph that represents the sunspot cycle from 1900 to 1990, then they are asked to graph the number of sunspots that occurred from 1995 to 2003 in order to understand...

Before the 17th century, people generally believed that Earth was at the center of the universe, a system originally developed by Ptolemy. Galileo, however, was not afraid to challenge existing beliefs when he published...