Highlights of the World Ephemeris for the 20th Century at Noon The World Ephemeris is the first computer calculated and typeset ephemeris with letter-quality printing. Now ease and clarity in reading is combined with accuracy and precision of data to provide the most complete and convenient ephemeris available for astrological calculation and analysis. The Sun's position is accurate to the second of arc; the Moon's mean Node and nine planetary positions are given to the minute of arc for every day of the 20th Century.