Thursday, February 28, 2019
The "We're Lagging Behind By 0.2422 Days" Story
It was an ordinary day. Last day of February which happens to be a Thursday this year. Next year this month will have a 29th day which we will need to keep the atomic clock in sync with...well...time. Everyone knows that a year lasts 365 days. Check your calendar if you're not sure. But, every four years we add a day to make sure we match up with a true year which is how long it takes the Earth to complete one orbit around the sun. New year will be a leap year and allow a birthday celebration for everyone who was born on February 29th. A solar year is 365.2422 days in length. That lag of 0.2422 days might seem small, but over time it adds up. If we wouldn't have leap years, our seasons would eventually be mixed up with snow in the summer and beach trips in the winter. But, is that all that bad? Might be easier for Santa to make his deliveries without having to worry about his sleigh getting stuck in the snow. If our calendar had never added a leap day, after three centuries January 1 would come in autumn. After six centuries it would land in summer. Happened in Rome in the 1st century BCE (before common era) when the calendar had slipped a full two months out of alignment with the seasons. So, in 46 BCE, Julius Caesar declared that the current year would last 445 days in order to bring the calendar back into alignment with the seasons. So what happened to everyone's birthday that year? And, what happened to those who were born during those 80 days that were never to be again? Boy, I would certainly complain if it were me who was born on one of those days. Well, some Romans were upset and they referred to this happening as the longest year in history and called it annus confusionis. The new calendar that Caesar instituted is known as the Julian calendar which adds a day every four years. So, that made each year 365.25 days long. That's still not the same as the solar year, so by the 16th century the error had added 10 extra days. In response, Pope Gregory XIII replaced the Julian calendar with the "Gregorian" one which introduced the modern schedule of leap days. So, to make this correction, October 4, 1582 was followed by October 15 and said that everyone born on those 11 days that were missed could celebrate their birthday on the 15th. Now, you know I made that up, right? So, when will we lose a few more days to make sure we don't have snow in August? I'm sure none of us will be around to see that. A few other Ancient people did try and make some different changes to keep the seasons in line with the calendar. The Hindu, Chinese and Hebrew calendars added leap months to keep pace with the seasons. Persian astronomer Omar Khayyam measured the length of the year as 365.24219858156 days and devised an elaborate leap-year schedule to match it. 36 years ago Russian math historians Adolph Yushkevich and Boris Rosenfeld analyzed Khayyam's scheme and deemed it superior in accuracy to the Gregorian calendar. So, now what will we do? Well, the new figures show our current calendar is accurate to one day in 3,333 years so that means we have until sometime around the year 5000 to decide whether to declare an extra leap day. And, if you happened to be born on that day, you would die before you were one year old. One more thing to consider is the leap second. On 27 occasions since 1972, the International Earth Rotation and Reference Systems Service (did you know we had one of these) has added an extra "leap" second into the length of a day. Seems that needed to keep the atomic clock in sync. The last leap second added was on December 31, 2016. I've lived almost 75 years now and I never knew that! And, to top that, another second will be added on June 30, 2020...maybe! No one is sure yet, except the time police. I just hope I'm on a beach somewhere when that happens. It was another extraordinary day, plus a second, in the life of an ordinary guy.
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