JULIAN CALENDAR

PART OF SERIES, "TRACKING TIME: BEHIND OUR CLOCKS AND CALENDAR"

Author: Ken Klark L. Flores

Introduction

The Julian calendar is a solar calendar introduced by Julius Caesar that used a 365-day year with a leap day added every four years, creating an average year of  (365.25) days. It replaced the older, less accurate Roman calendar and was used throughout the Roman Empire. While largely replaced by the modern Gregorian calendar, it is still used as a religious calendar by some Eastern Orthodox churches and by the Amazigh people (Origins of the Julian & Gregorian Calendars - Video & Lesson Transcript, n.d.)

Origins

This system is originated in 45 BC when a Roman Dictator Julius Caesar introduced it as a reform of the old Roman calendar. With help from the astronomer Sosigenes, it was a solar calendar that replaced the previous lunar-based system, establishing a 365-day year with a leap day added every four years (Julian Calendar | EBSCO, 2022). This system included the modern concept of 12 months and became the standard for many centuries, eventually being replaced by the Gregorian calendar due to its slight inaccuracy in tracking the solar year. 

The previous Roman calendar was a lunisolar system that relied on priests (pontifices) to insert intercalary months periodically to keep it aligned with the solar year. This power was often abused for political reasons, leading to a calendar that was several months out of sync with the actual seasons by the time of Caesar's reform in 46 BCE, a year that ended up being 445 days long to realign it (Ray, 2019; “Roman Republican Calendar | Chronology | Britannica,” 2019)

The Julian calendar brought uniformity and a stable timekeeping system across the Roman Empire and was used throughout most of the Western world for over 1,600 years.

System

A normal year has 365 days. A leap year of 366 days occurs every four years. The extra day was historically added by doubling February 24th (the "bissextile day"). However, this calendar had offset comes from overestimating the solar year by about 11 minutes, causing seasons to drift.

Reference

Origins of the Julian & Gregorian Calendars - Video & Lesson Transcript. (n.d.). Study.com. https://study.com/academy/lesson/origins-of-the-julian-gregorian-calendars.html

‌Julian Calendar | EBSCO. (2022). EBSCO Information Services, Inc. | Www.ebsco.com. https://www.ebsco.com/research-starters/history/julian-calendar

‌Ray, M. (2019). Julian calendar | History & Difference from Gregorian Calendar. In Encyclopædia Britannica. https://www.britannica.com/science/Julian-calendar

‌Roman republican calendar | chronology | Britannica. (2019). In Encyclopædia Britannica. https://www.britannica.com/science/Roman-republican-calendar

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