29 February, 2012

February 29, 3600

There is some likelihood that this day may need to be removed from the calendar.

As you all know, we commonly claim that an Earth year is 365.25 days long. Hence the reason we have a leap year every 4 years, and add an extra day.

Less well known is the fact that the Earth year is actually slightly less than 365.25 days long. Adding a leap year every 4 years means that we add an extra 3/4 of a day, every century. Thus, the further calendar correction that years divisible by 100, but not 400 are not leap years.

However, that correction doesn’t quite get us there either. It over corrects by 80 minutes every 400 years. Thus, in 7200 years, we’ll be off by a day again. At the half way point, year 3600, we should remove a leap day to get us back on track. And then repeat the process in years 10,800, 18,000, 25,200, etc.

I’m sure you’re all worried.

Of course, there’s also the possibility that in fact, we’ll need to do just the opposite and add in some more leap days by that time as the length of the year is increasing very slightly over time.

Stay tuned, this may be as big of a deal as Y2K. Stock up on your foodstuffs now. February 29, 3600 is a mere 1500 years from today!