Astronomy Picture of the Day

Explanation: Discovered by accident, this manuscript page provides graphical insight to astronomy in medieval times, before the Renaissance and the influence of Nicolaus Copernicus, Tycho Brahe, Johannes Kepler, and Galileo. The intriguing page is from lecture notes on astronomy compiled by the monk Magister Wolfgang de Styria before the year 1490. The top panels clearly illustrate the necessary geometry for a lunar (left) and solar eclipse in the Earth-centered Ptolemaic system. At lower left is a diagram of the Ptolemaic view of the Solar System with text at the upper right to explain the movement of the planets according to Ptolemy's geocentric model. At the lower right is a chart to calculate the date of Easter Sunday in the Julian calendar. The illustrated manuscript page was found at historic Melk Abbey in Austria.