Morning all,
I canât believe it is March already!
I wonder did any of you celebrate a birthday on Saturday?
Being born on the 29th of Feb must be so weirdâŚ
Câmere to meâŚ
Why do we have Leap Years? đ¸
The Maths.
âFor centuries, attempts to sync calendars with the length of the natural year have sowed chaosâuntil the concept of leap year provided a way to make up for lost time.â
(read more - The National Geographic)
The National Geographic has written a cool piece on the human element to telling time and recording calendars over the centuries, they go through the different evolutions across different civilisations.
The year 46 B.C. was an extra long one, as Caesar sought to fix the problem.
âCaesar adopted the system by decreeing a single, 445-day-long Year of Confusion (46 B.C.) to correct the long years of drift in one go. He then mandated a 365.25 day year that simply added a leap day every fourth year.â
(read more - The National Geographic)
But whatâs the issue, why the leap year?
Letâs do some maths, which will do all the explaining.
The solar year is 365.2422~ days longâŚ
âŚso not exactly 365! and this is the problem.
It would be completely impractical to ever have 0.2422 of a day, hence why a calendar must operate with whole numbers.
Breaking it down, 0.2422~ of a day is about 5hrs 48mins and 46secs.
Notice, however, that it is still not perfect⌠if the solar year was off by exactly 0.25 (1/4), then we would be off by 6hrs a year and an extra day every four years would solve it perfectly!
Each year we fall behind 5hrs 48mins and 46secs, so every four years we are off by 23hrs 15mins and 3secs ~
Therefore we add February 29th!
Isnât that a full day we have added? a full 24hrs?
I hear you, alas, this is where it gets confusing,
Now we are ahead of the solar year, and keeping with my rough calculations, 44mins 57secs ahead, every 4 years (having added the leap year).
What now?
As a solution to this, every 100 years (every 25 leap years) having amassed roughly 18hrs, we just donât add a day that yearâŚ
Well now we are behind again, by roughly 6 hours, so every 400 years (24hrs~~) we do have a leap year, and add a day!, thereby getting us back on track, albeit not exactly!
Confused? hopefully not.
(if you were to tell a computer to calculate whether a year is a leap year)
For a year to be a leap year:
The year must be divisible by 4
The year must NOT be divisible by 100
An exception to #2 - if the year is divisible by 100 AND 400, then it is a leap year.
Hence why the year 2000 was a leap year but 1900 wasnât (despite being divisible by 4)
Youâll probably never need that information.
It is interesting though that we are still off by minutes every 400 years, so sometime in the future when it adds up, they are going to have to take action to fix it.
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Taking the first bite of a burger determines where the front of it is.
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