Definition:Calendar/Julian/Year

Definition

A Julian year is the length of a year as defined using the Julian calendar.

$1$ Julian year $= \begin {cases} 366 \, \text {days} & : 4 \divides y \\ 365 \, \text {days} & : 4 \nmid y \end {cases}$

where:

$y$ denotes the number of the year

$4 \divides y$ denotes that $y$ is divisible by $4$

$4 \nmid y$ denotes that $y$ is not divisible by $4$.

Also known as

Some sources refer to a Julian year as a civil year.

However, the Julian year has not been used as the basis of the calendar for most societies for a number of centuries now, having been supplanted by the Gregorian year.

Also see

• Discrepancy between Julian Year and Tropical Year

• Results about Julian year can be found here.

Source of Name

The Julian year is named after Julius Caesar, under whose reign it was introduced.

Sources

• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $365 \cdotp 2422$
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $365 \cdotp 24219 \, 878$
• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): year
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): year