February 1, 2008
The Friday Flyer Editor
For all the trivia lovers out there, this is a significant month for a newspaper called The Friday Flyer because this February will have five Fridays. Not unusual, you say. Oh yes, it is. A February with five Fridays only comes around once every 28 years. The last year was 1980; the next will be 2036. The main reason for the oddity is because this is Leap Year!
Here are a few more frivolous but interesting facts provided by www.timeanddate.com. In the Gregorian calendar used by most modern countries, every year divisible by four is a leap year. Every year divisible by 100 is not a leap year Ė unless the year is divisible by 400, and then it is a leap year. That means 1600, 2000 and 2400 are leap years. Most people reading this actually experienced one of these remarkable dates.
According to astronomers, leap years are needed so that girls have a chance to propose to their guy at least once every four years . . . oops, thatís the folklore. The real reason is to keep the calendar in alignment with the earthís motion around the sun.
According to timeanddate.com, the vernal equinox is when the sun is directly above the Earthís equator. The mean time between two successive vernal equinoxes is called a tropical year, and it is about 365.2422 days long. Using a calendar with 365 days would result in an error of 0.2422 days, or almost six hours per year.
After 100 years, this calendar would be more than 24 days ahead of the seasons (tropical year), which would put Fiesta Day near the beginning of May instead of at the end of May. Eventually it would be celebrated in the middle of winter, which is not a desirable situation. Hence, itís important to align the calendar with the seasons and make the difference as small as possible.
So astronomers living as long ago as 238 BC, looking at the night sky under the rule of King Ptolemy III of Egypt, kept close records of the stars and did their math. Their calculations and that of their successors resulted in the Julian Calendar in 45 BC.
The math was pretty darn good Ė the vernal equinox was still right on as of 325 AD and the Council of Nicaea Ė but it wasnít good enough. The Julian Calendar had introduced too many leap days; so, a few centuries later, the vernal equinox no longer occurred on March 21.
When the Gregorian Calendar was first adopted in Italy, Poland, Portugal and Spain in 1582, 10 days were dropped in October. Imagine losing Halloween. Great Britain and the American colonies didnít adopt the new calendar until 1752, when 11 days had to be dropped in September.
Not to complicate matters, but the Gregorian calendar may need some modification a few thousand years ahead. A tropical year is approximately 365.242199 days, but it varies from year to year because of influence by the other planets.
The next question, of course, is why February only has 28 days to begin with, when other months have 30 or 31? To answer that question, one has to look beyond math to the egos of the Roman gods. We wonít go there.
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