Why February Has 28 Or 29 Days: Leap Year Explained
When this article releases, it is 28th of February, but February has 28 or 29 days, you can't say this article is released on the final day of February.
Oh really? Isn't that February has 28 days? Yes, usually. But in this year, 2024, there is a 29th of February.
It is weird that our calendar decides to make a mechanism that one month can have an additional day for a certain period. Why did we create this system? Why it is February? How do people born on the 29th of February celebrate birthdays?
Let us take a look at the special month of February, why February has 28 or 29 days.
This is Antlerium PotatoNews, a series focusing on the daily lives of ordinary people, including culture customs. Today we explore leap year, the mechanism that causes February to switch between 28 and 29 days.
Why does leap year exist?
Leap year is a year that has an extra day in order to synchronize the calendar with seasons for every year. A common year has 365 days, and a leap year has 366 days, and the added day is on the 29th of February.
A day and a year are two concepts. A day conceptually is the period the Earth rotates itself, and a year is the period the Earth orbits around the sun.
If we take this concept seriously, 1 year would be 365.2422 days. However, even if month and year can be set arbitrarily, day can't. We take the day-night cycle seriously and our biological clocks depend on it. Inventing a day with one fourth of the length brings more harm than good.
To tackle this problem, the Julian calendar introduced leap day. Since 45 BC, February has 28 or 29 days, usually, it has 28 days, but for every four years, it is added to 29.
Fun fact, when the Julian calendar first came out, people mistakenly believed that leap years happened every three years. Emperor Augustus had to cancel 3 leap years within 12 years and reinstate the right leap year system in 4 or 8 AD.
Alright, so leap years happened every four years, February has 29 days for every four years. Or is it?
Leap year every four years? The rules are more complicated than that
Following the system of the Julian calendar, the average length of year will be 365.25, longer than the actual days Earth takes to orbit around the sun (365.2422 days).
Discrepancy will eventually occur, and every 128 years there will have 1 day more than actual.
To solve this issue, when the Gregorian calendar we use today was released, 2 more rules were added.
- For every 100 years, one leap year is cancelled.
- For every 400 years, ignore the rule above.
That means that leap years every four years is not always the case.
Under these two new rules, when we reach the end of a century, the year that ends with -00 is a common year unless the year is divisible by 400.
For example, the year 2000 is a leap year, but years 2100, 2200, and 2300 are common years.
Why February has 28 or 29 days
To explain why it is February that has such arrangement, we must understand the history of February in our calendar.
In 713 BC, February was added to the Roman calendar with January, and the Roman calendar went from 10 months to 12 months. These two new months both have 28 days. It was not like February has 28 or 29 days because instead of leap day the Romans used intercalary month.
Originally, this was a month Rome performed expiatory sacrifices and ritual purifications. Therefore, Romans became increasingly disgusted with this month, treated it as an unlucky month.
When February was added in 713 BC, it was the last month of the calendar. It was not until 452 BC that February was placed between January and March.
When Julius Caesar introduced the Julian calendar, odd months had 31 days, and even months had 30 days, but that would be 366 days in a year, so the unsettling month of February was chosen to drop a day, and only in leap years it could have 30 days.
But when the Romans decided to give Augustus a month - August - the "month of Augustus", they wanted it to be as long as July, which is the "month of Julius Caesar". They flipped the number of days between odd and even months after July, but this arrangement will create 7 months with 31 days, and 366 days in a year. So they deleted a day from February forever.
That is how February becomes the shortest month of the calendar. That is why February has 28 or 29 days.
Weird phenomenon caused by February 29th
When February has 28 or 29 days. People dealing with anything relating to this particular day will get a little bit.... messy.
The most popular question would be how people born on the 29th of February celebrate their birthday. This is one of simplest question to answer in my opinion.
How do people born on the 29th of February celebrate birthdays?
People born on the 29th of February have the freedom to choose the 28th of February or the 1st of March to celebrate their birthday.
This is one of the most common questions to ask someone born on that day, also known as the Leaplings.
But for the law and administration, things get a little serious.
When do people born on the 29th of February become legally adults?
People born on the 29th of February do not have the freedom to choose the 28th of February or the 1st of March to be adults according to law and administration. Remember, 18 cannot be divided by 4, the year they turn 18 must be a common year.
Most countries recognize citizen born on the 29th of February to be adult starting on the 1st of March. This applies to Hong Kong, the UK and Australia.
Some places like Taiwan and New Zealand would use 28th of February as the legal birthday for the Leaplings.
What is the probability that a person born on the 29th of February
The actual chance of a person being born on the 29th of February is 97/146097, not 1/1461. It's smaller. The reason why people often mistake it for the latter is because they don't learn of the century rule mentioned above.
Share this article to your friends in case they get it wrong.
Take this month seriously
After reading the whole article you can see that February is an interesting month. The reason why February has 28 or 29 days can be traced back to the fact that the number of days our planet orbits the sun is not a natural number.
The modern calendar - Gregorian calendar - retains the Julian calendar's tradition of a leap year every 4 years, but adds two more rules. Years ending in -00 do not have leap days unless they are divisible by 400.
Ancient Romans' poor perspective toward February dooms it to be the month with the fewest days, but adding a leap day to the month makes it more special than any other month on our calendar.
The most special day on our calendar is definitely the 29th of February. February has 28 or 29 days, and the 29th is a rare occurrence. It brings struggles to the people born to this day to choose on which day to celebrate their birthday, and it brings struggles to countries to decide which date to identify the people born to this day as adults.
For those of you who were born on the 29th of February, you are special and lucky, luckier than 1/1461. Stay happy, stay strong, and be ready for your birthday tomorrow (this article went public on 28th of February, 2024).
This is the reason February has 28 or 29 days. To learn more about culture customs or other topics related to our ordinary life, make sure to follow PotatoNews. We will also post some cliffsnotes on our socials, make sure to follow them.
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