Editing Leap year (section)

==Julian calendar==
{{main|Julian calendar}}
On {{nowrap|1 January 45 BC}}, by edict, [[Julius Caesar]] reformed the historic [[Roman calendar]] to make it a consistent [[solar calendar]] (rather than one which was neither strictly lunar nor strictly solar), thus removing the need for frequent [[Intercalation (timekeeping)|intercalary months]]. His rule for leap years was a simple one: add a leap day every 4&nbsp;years. This algorithm is close to reality: a Julian year lasts 365.25{{spaces}}days, a [[mean tropical year]] about 365.2422&nbsp;days, a difference of only {{nowrap|{{midsize|≈}}{{hsp}}11{{midsize|{{frac2|4}}}} min}}.<ref>{{citation |date=2023 |title=Astronomical almanac online glossary |publisher=US Naval Observatory |url=https://aa.usno.navy.mil/faq/asa_glossary#year | access-date=15 August 2024 }}</ref> Consequently, even this Julian calendar drifts out of 'true' by about 3&nbsp;days every 400&nbsp;years. The Julian calendar continued in use unaltered for about 1600&nbsp;years until the Catholic Church became concerned about the widening divergence between the [[March Equinox]] and 21 March, as explained at [[Gregorian calendar]], below.

Prior to Caesar's creation of what would be the Julian calendar, February was already the shortest month of the year for Romans. In the [[Roman calendar]] (after the reform of [[Numa Pompilius]] that added January and February), all months except February had an odd number of days{{snd}}29 or 31. This was because of a [[Religion in ancient Rome|Roman superstition]] that even numbers were unlucky.<ref>{{Citation|title=Why Are There Only 28 Days in February? |encyclopedia=[[Encyclopedia Britannica]] |last=Hogeback |first=Jonathon |url=https://www.britannica.com/story/why-are-there-only-28-days-in-february |access-date=31 May 2023}}</ref> When Caesar changed the calendar to follow the solar year closely, he made all months have 30 or 31&nbsp;days, leaving February unchanged except in leap years.