Observation of the skies was necessary for devising calendars. Ancient agrarian peoples observed the heavens very closely to ensure properly timed planting and good harvests. They tracked the movements of the sun, moon, and stars, and pinpointed the changing of the seasons.
事實上，為了制訂曆法，早期農業民族都不得不觀測天象，掌握日月星辰變化，進一步抓住季節，讓播種、耕作宜時而豐收。