Rudolphine Tables

The Rudolphine Tables consist of a star catalogue and planetary tables published by Johannes Kepler in 1627, using observational data collected by Tycho Brahe (1546–1601). The tables are named in memory of Rudolf II, Holy Roman Emperor, in whose employ Brahe and Kepler had begun work on the tables. The main purpose of the Rudolphine tables was to allow the computation of the positions of the then known planets of the Solar System, and they were considerably more precise than earlier such tables. Previous tables Star tables had been produced for many centuries and were used to establish the position of the planets relative to the fixed stars (particularly the twelve constellations used in astrology) on a specific date in order to construct horoscopes. Until the end of the 16th century, the most widely used had been the Alphonsine tables, first produced in the 13th century and regularly updated thereafter. These were based on a Ptolemaic, geocentric model of the Solar System. Although the Alphonsine tables were not very accurate, nothing else was available and so they continued to be used. In 1551, following the publication of De revolutionibus orbium coelestium by Nicholas Copernicus, Erasmus Reinhold produced the Prutenic Tables based on a heliocentric model of the Solar System, but these were no more accurate than the earlier tables.