At one time people observed a 355-day calendar with an extra 22-day month every two years. But in 45BC Julius Caesar ordered his astronomer, Sosigenes, to simplify things.
Julius Caesar added the extra day is added to February because it used to be the last month of the Roman calendar.
Leap Day occur once every 4 years to keep our calendars in sync….That’s not exactly correct. The leap year’s extra day is vital because a complete orbit around the sun takes slightly longer than 365 days – 5 hours, 48 minutes, and 46 seconds longer, to be exact.
There's a Leap Day added every four years unless the year is perfectly divisible by 100, in which case there's no Leap Day. Unless the year is also perfectly divisible by 400, in which case the previous rule is nullified and there is a Leap Day. So 2000 had a February 29th because it was perfectly divisible by 400, while 2100 won't have one because it's only perfectly divisible by 100.
The last time a Leap Day was skipped was in February of 1900. The next time Leap Day will be skipped will be on February of 2100.
Some fun facts:
In 1288 Queen Margaret of Scotland at the age of 5 declared that a woman could propose to any man she liked on February 29. “The February 29 proposal” She ruled that men who refused the proposal would need to pay a fine.
In Italy legend has it that women are erratic during a leap year and several proverbs warn against planning important life events in a leap year.
In Greece leap year is believe to be bad luck.
In China they believe that children born in a leap month are harder to bring up.
In Russia it is believed more freak weather patterns happen in a leap year.
In Scotland farmers believe leap years are bad for crops and livestock, old proverb: “Leap year was ne’er a good sheep year.”
In Taiwan it is believed the lunar month can bring bad health to parents. As a tradition married daughters return home during the leap month to look after their parents.
In the U.S., leap year coincides with presidential election years.
Farmer folklore says beans and peas planted in a leap year “grow the wrong way”.
February 29 in known as Rare Disease Day.
The frog is a symbol associated with February 29.
Leap Years are the only years where January 1st and December 31st are on different days of the week every other year they're on the same day. So to tell if it's a Leap Year or not is by what day of the week the year starts and ends on.
Anthony, Texas is the self-proclaimed "Leap Year Capital of the World".
If you're on a fixed annual wage you work for free on Leap Day.
Prisoners serving a 1 yr sentence must serve the extra day if their term crosses leap day.
If you are born on February 29 you are known as "leaplings" or "leapers".
If you are born on February 29 you are not a leap year baby you are a leap DAY baby. If you are born any other day of that year you are a leap YEAR baby.
The chance of being born on a leap day is one in 1,461.
About four million people worldwide have a February 29th birthday.