What Is A Leap Year? And Its History something i never eally thought about.

[Saint_Michael 3]

By definition a leap year (or intercalary year) is a year containing an extra day or month in order to keep the calendar year in sync with an astronomical or seasonal year which follows the gregorian calendar.

The Gregorian calendar is the standard calendar that is used by most of the world and which in 1582, Pope Gregory XIII made it law that everyone should follow it due to the fact that the julian calendar was to long thus the vernal equinox (Beginning of Spring) kept going backwards due to the Shifting of the earth Rotation.

The Julian Calendar was introduce by Julius Caeser in 46AD to track the tropical year which is how long it takes for the sun (as seen by earth) to return to the same position on the ecliptic (its path among the stars on the celestial sphere).

So how does a leap year work well every 4th year or any year that can be divided by 4 is given an extra day which is February 29th. This also happens every 400 years as well; which happened in 2000. So in 400 years or 2400 AD we will have another leap as well. (just to be clear its only 1 day for the 4 century mark not 2).

So why does it matter that we have a leap year well the follow info will tell you why.

The Gregorian calendar is designed to keep the vernal equinox on or close to March 21, so that the date of Easter (celebrated on the Sunday after the 14th day of the Moon that falls on or after 21 March) remains correct with respect to the vernal equinox. The vernal equinox year is currently about 365.242375 days long.
The Gregorian leap year rule gives an average year length of 365.2425 days.
This difference of a little over 0.0001 days means that in around 8,000 years, the calendar will be about one day behind where it should be. But in 8,000 years' time the length of the vernal equinox year will have changed by an amount we can't accurately predict (see below). So the Gregorian leap year rule does a good enough job.

But a interesting thing could possible happen in the year 2800 with the calendar but im still not clear of it after reading it several times though but go to this link though.

https://en.wikipedia.org/wiki/Revised_Julian_calendar

but here is a interesting thought about birthdays that happen on 29th of feb:

A person who was born on 29 February may be called a "leapling". In non-leap years they usually celebrate their birthday on 28 February or 1 March.
There are many instances in children's literature where a person's claim to be only a quarter of their actual age turns out be based on counting their leap-year birthdays. A similar device is used in the plot of the Gilbert and Sullivan operetta The Pirates of Penzance.

To read more about the Leap I recommend these sites:


https://en.wikipedia.org/wiki/Tropical_year
https://en.wikipedia.org/wiki/Gregorian_calendar]Read More about the Gregorian Calender
https://en.wikipedia.org/wiki/Julian_Calendar
https://en.wikipedia.org/wiki/Leap_year
https://en.wikipedia.org/wiki/Revised_Julian_calendar

[Mysterio 0]

Very well said. Also leap year has been used i know for hundreds of years. It is to help make sure we keep in track for a year is really should be 365.2 Days Long or something like that. Thanks for this great summary of it. This is very helpfull.- Mysterio

[DogEater008 0]

i didn't get what you meant about every 400 years. A year is actually 365 days and 6 hours (6x4=24 or 1 day). So every four years, they have to add one extra day. Or else the calender will be messed up in a few thousand year (like summer will actually be in the winter.. this is just an example).

[kasm 0]

i didn't get what you meant about every 400 years.

 

A year is actually 365 days and 6 hours (6x4=24 or 1 day). So every four years, they have to add one extra day. .......

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Here will find my answer to DogEater008's question tha is why every 400 we add one day:

 

It is because The Gregorian calandar gives an average year length of 365.2425 days. And by adding 1 days for each 4 years, we in fact considered the year of length of 365.25 days. instead of 365.2425 days. with difference about .0075 extra. Then when we don't add the leap in the year dividisable by 100, we take of .01 instead of .0075 day with difference .0025 day which can be corrected by add 1 day every 400 years.

 

Remember that even 365.2425 is different than the exact 365.242375 so all the above has another difference .000125 day which can be corrected every 800 years. This may be the answer to Saint_Michaels question about year 2800.

But a interesting thing could possible happen in the year 2800 with the calendar but im still not clear of it after reading it several times though but go to this link though.

[unicornrose 0]

I kind of had a little idea about leap year before. I knew it was meant to keep us from falling behind. What I did not realize was how recent in history that many countries had actually adopted the calander. I love this kind of thing. Its so facinating. Thank you for sharing.

[eee 0]

kinda knew that but propz

[inyourarms 0]

That's interesting, I always wondered about that..