Saturday, February 28, 2015

Why does February have 28 days?

Have you ever wondered why we have the calendar we do? Most of the names for the months come from Roman or Greek deities (January, March, May, June) while a couple are named for emperors (July and August) and others are named for Roman numbers (September, October, November, December). February is named for the Latin term meaning purification and refers to the purification ritual Februa, on February 15 (full moon) on the old Roman lunar calendar. The origin of the name for April is unknown. Have you ever wondered why February has only 28 days? And 29 days in a leap year? The answer is fairly simple: superstition and the lunar cycles.


Ancient Romans used the 10 month calendar of Romulus of 304 days from March, with the spring equinox through December with each month either 30 or 31 days. In 713 BCE, King Numa Pompilius decided to reform the calendar with the year’s 12 lunar cycles, a span of about 355 days and introduced January and February. He believed the Ancient Roman superstition that even numbers were unlucky, so Numa tried to make each month odd but to reach the quota of 355 days, one month had to be even and February was chosen.


February soon became a month of rituals in order to ward off the bad omens from having even number of days. After a few years, the King Numa’s calendar was out of sync with the seasons. The Romans occasionally insert a 27 days leap month called Mercedoniaus. This new calendar caused so much confusion and headaches, that Caesar nixed the leap month and reformed the calendar again. By 46 BCE, Caesar aligned the calendar with the sun and added a few days to up to 365 but kept February 28 days long.


The leap year was introduced by Julius Caesar over two thousand years ago. There was only one rule: the leap year would be any year divisible by 4. This lead to too many leap years and wasn’t corrected until the introduction of the Gregorian calendar, in 1582, which allowed for realignment of the astronomical events like the solstices and equinoxes. The Gregorian calendar, named for Pope Gregory XIII has three rules for a year to be a leap year or not: 1) the year is evenly divisible by 4, 2) if the year is evenly divisible by 100, it is not a leap year, unless, 3) the year is evenly divisible by 400, then it is a leap year. So, the years 1900, 2100, and 2200 are not leap years but 1600, 2000, and 2400 are leap years.


Whew, confused? My head’s spinning a little bit. So, the adage that a leap year is every four year is not entirely accurate. So when someone asks you why February has 28 days and 29 days in a leap year, you could give them the long and confusing history behind the calendar’s development. Or you can simply say it is in accordance with astronomical events.