calendar vs ephemeris

calendar

verb
  • To set a date for a proceeding in court, usually done by a judge at a calendar call. 

  • To enter or write in a calendar; to register. 

noun
  • An orderly list or enumeration of persons, things, or events; a schedule. 

  • Any system by which time is divided into days, weeks, months, and years. 

  • An appointment book (US), appointment diary (UK) 

  • A list of planned events. 

  • A means to determine the date consisting of a document containing dates and other temporal information. 

ephemeris

noun
  • Computer software that calculates the apparent position of celestial bodies. 

  • A table giving the apparent position of celestial bodies throughout the year; normally given as right ascension and declination. 

How often have the words calendar and ephemeris occurred in a corpus of books? (source: Google Ngram Viewer )