An Extra Day in Our Lives

Today, I am taking a little privilege with the “devotion” and turning it into a history lesson. February 29th only comes around every four years and since this is my usual day to post, I thought it was appropriate; besides today is also my birthday. I posted most of this history four years ago but it was worth doing again since many more people are reading this blog today than there were four years ago. The chances of having a birthday on February 29th are 1:1500; please indulge me.

The leap year’s extra day is necessary because of our Solar System. One earth year does not take an exact number of whole days; it takes 365.2422 days, plus or minus. It wasn’t until Julius Caesar came to power that changes were made. People observed a 355-day calendar – with an extra 22-day month every two years. This was not a solution to the celestial problem since feast days began sliding into different seasons. So Caesar ordered his astronomer, Sosigenes, to simplify things. Sosigenes opted for the 365-day year with an extra day every four years to scoop up the extra hours. This is how the 29th day in February was born. It was then fine-tuned by Pope Gregory XIII. Check this out:

Every fourth year is a leap year, as a rule of thumb. But that’s not the end of the story. A year that is divisible by 100, but not by 400, is not. So 2000 was a leap year, as was 1600. But 1700, 1800 and 1900 were not leap years. “It seems a bit arbitrary,” says Ian Stewart, emeritus professor of mathematics at Warwick University. But there’s a good reason behind it. “The year is 365 days and a quarter long – but not exactly. If it was exactly, then you could say it was every four years. But it is very slightly less.” The answer arrived at by Pope Gregory XIII and his astronomers when they introduced the Gregorian calendar in 1582, was to lose three leap days every 400 years. The math has hung together ever since. It will need to be rethought in about 10,000 years’ time, Stewart warns. But by then mankind might have come up with a new system.

Why is February 29, not February 31, a leap year day? All the other months have 30 or 31 days, but February suffered because of the ego of Roman Emperor Caesar Augustus. Under Julius Caesar, February had 30 days, but when Caesar Augustus was emperor he was upset that his month – August – had only 29 days.  Compare this to the month named after his predecessor Julius (July) which had 31. “He pinched a couple of days for August to make it the same as July. And it was poor old February that lost out,” says Prof Stewart.

So today, I find myself traveling again but this year I have my wonderful wife by my side. We’re headed to California to enjoy the weather and do a little work. We are trying to do the impossible – work together. I couldn’t think of a better birthday gift.


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