**Why are there leap days? Why is there a leap year and why is there a leap month?** **Let’s find out what leap day is.**

In the solar calendar **, there is a leap year every 4 years, adding to February a day that is called a leap day.**

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To know which year of the solar calendar is a leap year, we just need **to take the number of that year’s table and divide it by 4** , which is enough, then that year is a leap year in February, adding 1 day to 29 days. Because normally February is only 28 days. Example: 1996 is a leap year? We take the number of calendar year 1996 divided by 4, it’s exactly 499 times. So 1996 was a leap year.

But note that **for the full years of the Century** (ie the number of that year has 2 zeros at the end, we have to **take the first 2 digits of the number to divide by 4.** If divided enough, that year has a leap year. .

Also, there are some exceptions to this rule because a calendar year is slightly shorter than 365.25 days. Years that are divisible by 100 are only considered leap years if they are also divisible by 400. For example, 1600 and 2000 are leap years but 1700, 1800 and 1900 are not. Likewise, 2100, 2200, 2300, 2500, 2600, 2700, 2900 and 3000 are not leap years but 2400 and 2800 are leap years. According to this principle, an average year has 365 + 1/4 − 1/100 + 1/400 = 365.2425 days, which is 365 days 5 hours 49 minutes and 12 seconds.

That’s because **the Gregorian calendar** was created to ensure that the vernal equinox in Europe falls on March 21, to ensure that Easter can be adjusted to the vernal equinox more clearly.

A vernal equinox year (calculated between two successive vernal equinoxes) is approximately 365,242375 days.

The Gregorian leap year rule takes an average year of 365.2425 days.

This very small difference (over 0.0001 days) means that the time error will accumulate for a full day in about 8,000 years. But over a period of 8,000 years, the length of a vernal equinox will also vary by an amount that cannot be accurately predicted in advance. So the rule for calculating leap years of the Gregorian calendar is sufficient.

So it’s very easy to know which year is a leap year, right? The question of why there are leap days has been solved. Hope to bring you useful knowledge in life.

**A leap year is a year:**

**A leap month is a month:**

More specifically, change depends on factors such as post-glacial rebound and sea level rise because of climate change. We cannot predict these changes accurately enough to be able to make calendars accurate to the day for tens of thousands of years.

In the calculation of the Gregorian calendar is influenced by the Julian calendar used by the Romans. While the Roman calendar is derived from the lunar calendar (although from the 5th century BC it no longer follows the lunar cycle) and named for the days after the three weeks of the lunar cycle.

The days were counted down (including this one) until the next named day, so February 24 was *ante diem sextum calendas martii (“the Friday before the calendar of March”).*

Leap Day – A special day that comes once every 4 years.

Since 45 BC, February in leap years has two days known as the “Friday before the calendar of March”. The redundant day was originally the second of such so-called days, but since the 3rd century it has been the first. Hence the term leap day for February 24 in leap years.

When this custom was followed, the holidays following the addition were moved in leap years. For example, the previous feast day of Saint Matthias, on 24th February in common years would fall on 25th February in leap years.

However, this historical delicacy is in the process of being eliminated: the European Union announced that, from 2000, February 29 will be a leap day rather than February 24, and the Catholic Church Rome now also uses February 29 as a leap day. The obvious difference is only in countries that celebrate “named day”.

The adjustment of the annual calendar to match the rotation of the Earth. Two Johns Hopkins University professors wished to do so with a calendar system that did not include leap years, which would not have to be changed until later; February 2 of each year will always fall on a Tuesday.

To match the rotation of the Earth, the two professors added a leap week every 5 or 6 years. That is, every decade, we will only have to face a leap week.

Kodak founder George Eastman also proposed a calendar of his own: Fixed International Calendar with a fixed 28 days/month, a year with a total of 13 months with the “13th month” named Sol, located between July and August; At the end of each year there is a leap day used as a holiday. This calendar also still has a leap day after 4 years.

Happy special day only once every 4 years – **Leap Day 2020!**

**Only about 5 million people worldwide were born on February 29, with an odds of 1/1,461** . Some famous people born on this day include: actress and singer Dinah Shore (born 1916), speaker Tony Robbins (born 1960) and hip-hop artist Ja Rule (born 1976).

Technically, birthdays are only celebrated once every four years, but they are part of an elite group. In countries that use the same lunar calendar, people born on Lead day can celebrate their birthdays every year according to the lunar calendar.