February 28, 2017 is the last day of the month this year, because there is no February 29, 2017. This year is not a leap year and we don’t have another one until 2020, which gives us the next February 29. Leap years aren’t that uncommon, since they happen every four years, and the reason we have them is pretty simple. We just have to make up for lost time our 365-day calendars.
Here’s a look at leap days and why we don’t have one this year.
1. Leap Days Happen Every 4 Years
Leap years only happen every four years, meaning that there’s no Leap Day in 2017. The next Leap Day is February 29, 2020.
As InfoPlease explains, the leap years are needed to make sure the Gregorian calendar works because the actual time it takes for the earth to go around the sun is not exactly 365 days. It takes exactly 365 days, 5 hours, 48 minutes, and 46 seconds. Since we don’t mark “quarter days” on our calendars, we have to make up that lost 5 hours and 48 minutes with an extra day in February every four years.
The Ancient Egyptians did try to introduce the idea of a “leap year,” but it wasn’t implemented well. In 25 BCE, Roman Emperor Augustus was more successful, and that’s where the idea of February 29 being “Leap Day” came into play.
2. There Are Some Leap Years Without a ‘Leap Day’
To make things more confusing, there are actually Leap Years that do not include Leap Days. This is because the real length of the solar year is 11 minutes and 14 seconds left than 365 and a quarter days.
The creators of the Gregorian calendar figured out that they could fix this situation by skipping a leap year every 400 years. These years have to be divisible by 400. So, 16000 and 2000 were leap years, but 1700, 1800 and 1900 weren’t. The next leap years without a leap day are 2100, 2200 and 2300.
3. If You’re Born on a February 29, Your Birthday is Considered March 1 in Some States
If you’re born on February 29, you get to be called a “leaper” if you want. Some might chose to celebrate their birthdays on February 28, and others can go with March 1. There are plenty of celebrities who were born on February 29, including motivational speaker Tony Robbins, Foster the People’s Mark Foster and rapper Ja Rule.
While it might sound fun to be born on the Leap Day, it does have its complications. Individual states get to decide if March 1 is your real birthday and many do. According to The Atlantic, there are at least 187,000 people in the U.S. who were born on February 29. The odds of being born on that day are 10in-1,461.
4. Lunisolar Calendars Have Leap Months Instead of Just 1 Day
While solar calendars only have to add in a day every four years, lunisolar calendars like the Chinese and Hebrew calendars add an extra month. The extra month is called an “embolismic month.”
In the Hebrew calendar, the extra month is called “Adar Alef” and is added before the month Adar. On the leap year Hebrew calendar, Adar is renamed Adar Bet (or “Second Adar”). The month is added seven times every 19 years. That way, Passover is always in the spring, as the Torah requires.
5. In 1912, Swedes Celebrated February 30
Yes, one year, there was a real February 30. It was celebrated in Sweden in 1712, when Finland was part of the country.
It wasn’t until 1700 that Sweden and Finland officially switched from the Julian Calendar to the Gregorian Calendar. The Swedish Empire decided to not mark any leap days between 1700 and 1740. However, they marked the leap days in 1704 and 1708. So in 1712, they reinstated the Julian calendar for a year. It was already a leap year in the Gregorian calendar, but they added another day, creating February 30. Sweden finally finished converting to the Gregorian calendar in 1753, when they dropped the last 11 days of February.
In 1930 and 1931, the Soviet Union had a February 30 on the revolutionary calendar, which had five-day weeks. Although the calendar was in existence until 1940, there was evidence that people still used the Gregorian Calendar during this time.