The Julian calendar is a reform of the Roman calendar introduced by Julius Caesar in 46 BC (708 AUC). It took effect the following year, 45 BC (709 AUC), and continued to be used as the civil calendar in some countries into the 20th century. The calendar has a regular year of 365 days divided into 12 months, as listed in Table of months. A leap day is added to February every four years. The Julian year is, therefore, on average 365.25 days long.
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The Julian calendar is a reform of the Roman calendar introduced by Julius Caesar in 46 BC (708 AUC). It took effect the following year, 45 BC (709 AUC), and continued to be used as the civil calendar in some countries into the 20th century. The calendar has a regular year of 365 days divided into 12 months, as listed in Table of months. A leap day is added to February every four years. The Julian year is, therefore, on average 365.25 days long.
The calendar year was intended to approximate the tropical (solar) year. Although Greek astronomers had known, at least since Hipparchus, that the tropical year was a few minutes shorter than 365.25 days, the calendar did not compensate for this difference. As a result, the calendar year gained about three days every four centuries compared to observed equinox times and the seasons. This discrepancy was corrected by the Gregorian reform, introduced in 1582.
The Julian calendar has been replaced by the Gregorian calendar in all countries which...
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