闰年闰日背后的科学和历史

Today is February 29th - Otherwise known as a 'Leap Day'.

February 29th is a date that only occurs every 4 years, meaning that an extra day is added to the calendar. This means 2012 is 366 days long as opposed to the usual 365.

Astronomer, Dr. Meghan Gray from Nottingham University explains the reason is all to do with complicated Science and Mathematics.

"Our Year is made up of about 365 and a quarter days………"

This adjustment does a pretty good job at remedying the extra day accumulated.

However, the exact time it takes the earth to move round the Sun is 365.242. Meaning that if we add a full day every four years, we are actually adding too much time. Meaning that every 100 years, we need to take that day away again.

This rule is once again challenged every 400 years, such as in the year 2000, when we have then taken too much time away and so we have to add it back in on to a year that would have normally been a Leap year.

Dr Gray summarises the Math.

"This becomes very complicated but...."

Julius Caesar was behind the origin of adding a day every four years. The early Romans had a 355 day calendar and to keep festivals occurring around the same season each year a 22 or 23 day month was created every second year. Julius Caesar decided to simplify things and added days to different months of the year to create the 365 day calendar, the actual calculation were made by Caesar's astronomer, Sosigenes.

Julius Ceasar proclaimed that every fourth year following the 28th day of Februarius (February 29th) one day was to be added, making every fourth year a leap year.

And so, every four years, the world gains an extra day on February 29th. This has allowed many traditions to spawn around the world related to the special date.

In Ireland for example, many observe a switching of traditional romantic gestures as was portrayed cinematically in the film 'Leap Year' starring Amy Adams.

The tradition begun back in Ireland in the 5th century when St. Bridget tried convincing St. Patrick that women should be allowed to propose marriage at least once day a year. St. Patrick relented, but with a catch - Women could only have the opportunity every four years on leap day.

The tradition continued, and in 1288 Scotland passed a law that gave women the legal right to propose on leap day. And if the man refused, he was fined!
This folk-lore is also observed in the UK, Finland and Denmark.

Meanwhile, in Greece, it is considered unlucky to get married during a Leap Year.

Those born on February 29th are often referred to as 'Leapers' or 'Leaplings'.

Over 200,000 people in America are 'Leapers'. Most of them celebrate it on February 28th or March 1st. In China, those born on February 29th legally have their birthday on February 28th in normal years.

and so we Say Happy Leap Day and Happy Birthday to all listeners who are celebrating their Birthday today.

Here's to the next one in 2016.

For CRI, I'm Brandon Blackburn-Dwyer.