ALFONSINE TABLES

also spelled Alphonsine Tables, set of astronomical tables prepared in Toledo, Spain, for King Alfonso X of Len and Castile under the direction of Jehuda ben Moses Cohen and Isaac ben Sid. Completed in 1252, these tables were based on the Ptolemaic theory, which assumed that the Earth was at the centre of the solar system. They enabled astronomers to calculate eclipses and the positions of the planets for any given moment. The original form of the tables was cast into a handier arrangement in Paris around 1320, and manuscript copies of this version rapidly propagated throughout Europe. For more than two centuries they were considered the best astronomical tables available. They were first printed in 1483. The tables were an important source of information for the young Copernicus, but his own work superseded them in the 1550s.