Leap Year? Why?

Thirty days hath September
April, June, and November,
All the rest have thirty one,
Except February alone,
Which hath twenty eight days clear,
And twenty-nine in each leap year.

Why do we need Leap Years?

Leap Years are needed to keep our calendar in alignment with the Earth's revolutions around the sun.
It takes the Earth approximately 365.242199 days (a tropical year) to circle once around the Sun.

However, the Gregorian calendar has only 365 days in a year, so if we didn't add a day on February 29 nearly every 4 years, we would lose almost six hours off our calendar every year. After only 100 years, our calendar would be off by approximately 24 days!
How do we calculate Leap Years?

In the Gregorian calendar 3 criteria must be met to be a leap year:
The year is evenly divisible by 4;
If the year can be evenly divided by 100, it is NOT a leap year, unless;
The year is also evenly divisible by 400. Then it is a leap year.

This means that 2000 and 2400 are leap years, while 1800, 1900, 2100, 2200, 2300 and 2500 are NOT leap years.

The year 2000 was somewhat special as it was the first instance when the third criterion was used in most parts of the world since the transition from the Julian to the Gregorian Calendar.
Who invented Leap Years?

Julius Caesar introduced Leap Years in the Roman empire over 2000 years ago, but the Julian calendar had only one rule: any year evenly divisible by 4 would be a leap year. This lead to way too many leap years, but didn't get corrected until the introduction of the Gregorian Calendar more than 1500 years later.


Leap Year Traditions.

Women can propose to men

According to an old Irish legend, or possibly history, St Bridget struck a deal with St Patrick to allow women to propose to men – and not just the other way around – every 4 years. This is believed to have been introduced to balance the traditional roles of men and women in a similar way to how Leap Day balances the calendar.

In some places, Leap Day has been known as “Bachelors’ Day” for the same reason. A man was expected to pay a penalty, such as a gown or money, if he refused a marriage proposal from a woman on Leap Day. During the middle ages there were laws governing this tradition.

In many European countries, especially in the upper classes of society, tradition dictates that any man who refuses a woman's proposal on February 29 has to buy her 12 pairs of gloves. The intention is that the woman can wear the gloves to hide the embarrassment of not having an engagement ring.

Bad luck

In Scotland, it used to be considered unlucky for someone to be born on Leap Day, just like Friday 13th is considered an unlucky day by many. In Greece it’s said to be unlucky for couples to marry during a Leap Year, and especially on Leap Day.

Leap Day is also St Oswald’s Day, named after an archbishop of York who died on February 29, 992. The memorial is celebrated on February 29 during Leap Years and on February 28 during common years.
Leap Day birthdays

People born on February 29 are all invited to join The Honor society of Leap Year Day Babies.

According to the Guinness Book of Records, there are record holders both of a family producing three consecutive generations born on February 29 and of the number of children born on February 29 in the same family.