Early Observations and Modern Ephemerides

Abstract

AbstractThere is a great variety of planetary and lunar observations recorded throughout history. Even today, some of these are useful for the improvement of ephemerides, though one must use a lot of judgment and caution - for surprising reasons. Five different sets of observations are presented, each with a story and a lesson: Galileo’s observations of Neptune, Lalande’s observations of Neptune, Williams’ measurements of the 1780 solar eclipse, Robertson’s 1811 transit timings, and solar eclipses in general.