‘Out of a greate laborinth of errors’: Lunar astronomy in London before Kepler

Abstract

Johannes Kepler is considered to be the first scholar to have offered an adequate description of heavenly phenomena observed on the Moon's sky. Kepler outlined his ideas in his Somnium ( The Dream ), written originally in 1609, and subsequently printed in the years 1630/34. Kepler's lunar astronomy was to expose the absurdity of the arguments that the geocentric theatre of heavenly phenomena proves that the Earth remains motionless. In this paper, I argue that at the turn of the seventeenth century the idea of the sky observed from the Moon's surface was explored in cosmological discourse far more often than it has been assumed so far. My argument derives from the manuscript treatise Astrostereon (1603) authored by an English astrologer and physician, Edward Gresham. Writing for the same purpose as Kepler but several years earlier, Gresham laid down the foundation of lunar astronomy. I also demonstrate the uses of lunar astronomy in astrological almanacs printed in London at the time when Kepler's ideas were not widely known.