1 Introduction The entire enterprise of determining the orbits of planets, asteroids and comets is quite a. fundamental ephemeris computations Full-text links:Free Ephemeris DownloadGps Ephemeris DownloadChapter 1 Introduction 1.. Tfr000 (talk) 19:46, 8 February 2012 (UTC). Although there is no fundamental reason why the solar system should not sometime receive a cometary visitor from interstell..