Why is there a leap day

Why Do We Have Leap Year?

The Gregorian calendar, which now serves as the standard calendar for civil use throughout the world, has both common years and leap years. A common year has 365 days and a leap year 366 days, with the extra— or intercalary— day designated as February 29.

A leap year occurs every four years to help synchronize the calendar year with the solar year, or the length of time it takes to complete the Earth’s orbit around the sun, which is about 365 days and a quarter of a day.

The length of the solar year, however, is slightly less than 365¼ days-by about 11 minutes. To compensate for this discrepancy, the leap year is omitted three times every four hundred years.

In other words, a century year cannot be a leap year unless it is divisible by 400. Thus 1700, 1800, and 1900 were not leaped years, but 1600, 2000, and 2400 are leap years.

Source- https://www.infoplease.com/

What is Leap Year?

A leap year consists of 366 days as opposed to a ‘regular’ year that consists of 365 days. Every 4 years, a year comes along that has one more day to it, meaning 366 days in total. Those years with 366 days are leap years. More specifically, the year in which the month of February has 29 days (instead of the usual 28 days) is deemed a leap year. For example, the year 2016 was a leap year.

How often is leap year?

A leap year comes every 4 years. A normal year has 365 days, but every 4 years, a leap year comes which has 366 days, i.e. 1 day more than a normal year.

When is the next leap year?

The next leap year is 2020. The last leap year was 2016, and since leap years come after 4 years, so the next leap year will come in 2020. (2016+4)

When is the next leap day?

The next leap year will be February 29, 2020. Leap days come after 4 years. Since the last leap day was 29 Feb 2016, the next leap day will be in the year 2020.

Source: https://www.scienceabc.com/

In 2020, February gets an extra day. Instead of 28 days, this year February will have 29 days. Almost everyone if familiar with the concept of leap year, but the reasoning behind it is a little complicated. For example, most people believe that leap year occurs once every four years, but that’s not always the case. What’s going on and why do we have leap year?

A calendar year is typically 365 days long. These so called “common years” loosely define the number of days it takes the Earth to complete one orbit around the Sun. But 365 is actually a rounded number. It takes Earth 365.242190 days to orbit the Sun, or 365 days 5 hours 48 minutes and 56 seconds. This “sidereal” year is slightly longer than the calendar year, and that extra 5 hours 48 minutes and 56 seconds needs to be accounted for somehow. If we didn’t account for this extra time, the seasons would begin to drift. This would be annoying if not devasting, because over a period of about 700 years our summers, which we’ve come to expect in June in the northern hemisphere, would begin to occur in December! 

By adding an extra day every four years, our calendar years stay adjusted to the sidereal year, but that’s not quite right either. Some simple math will show that over four years the difference between the calendar years and the sidereal year is not exactly 24 hours. Instead, it’s 23.262222 hours. Rounding strikes again! By adding a leap day every four years, we actually make the calendar longer by over 44 minutes. Over time, these extra 44+ minutes would also cause the seasons to drift in our calendar. For this reason, not every four years is a leap year.  The rule is that if the year is divisible by 100 and not divisible by 400, leap year is skipped. The year 2000 was a leap year, for example, but the years 1700, 1800, and 1900 were not.  The next time a leap year will be skipped is the year 2100.  

And why is it called “leap year?”  Well, a common year is 52 weeks and 1 day long.  That means that if your birthday were to occur on a Monday one year, the next year it should occur on a Tuesday. However, the addition of an extra day during a leap year means that your birthday now “leaps” over a day.  Instead of your birthday occurring on a Tuesday as it would following a common year, during a leap year, your birthday “leaps” over Tuesday and will now occur on a Wednesday.  

And if you happen to be born on leap day February 29, that doesn’t mean you only celebrate a birthday every four years.  Every three years, you get to celebrate your birthday on March 1 and continue to grow old like the rest of us.

Thanks to leap year, our seasons will always occur when we expect them to occur, and our calendar year will match the Earth’s sidereal year.  

Source: https://airandspace.si.edu/