Julian period

The Julian period is a method used by astronomers to standardize dates over long time spans. It combines three key calendars—the Julian calendar, the oldest calendar system, and the Gregorian calendar, which replaced it—and adds a fixed number (Julian day number) to create a continuous count of days. This system starts from a specific historical date in 4713 BCE and counts every day sequentially, making it easier to compare dates from different eras and calendars without confusion. It’s mainly used in astronomy and historical research to ensure precise, unambiguous dating across millennia.