The current decade does not end on December 31, 2019, but on December 31, 2020.

We seem to measure decades by the last two digits of the calendar year. Thus the 2010 decade will end December 31, 2019 and the new decade will start January 1, 2020. That is not really so, but it is so. We all “thought” Y2K ended December 31, 1999, but that was not so; it ended December 31, 2000; however no one celebrated it then since it was already celebrated a year earlier.

The calendar started on the first day of year 1 so the end of the first year was December 31, 1. Following this forward the end of the 10th year was December 31, 10. But January 1, 10 was assumed to be the start of the second decade – the decade of the 10s.

Now there are a few other things wrong about the calendar, but we accept the conventional “knowledge” and go along with what everybody assumes. For instance, the years are counted BC and AD. BC means Before Christ and AD means Anno Domini, Year of Our Lord, referring to Christ’s year of birth. However, it is now generally believed that Christ was born somewhere between 4 BC and 8 BC. The calendar was almost flawed from the beginning when Dionysius Exiguus around 529 AD was tasked with determining a calendar and decided to count the years from Christ’s birth. He used the reigns of each pope as his guide but he made a mistake and left off a pope that served four years, so almost right from the beginning, Christ was born 4 BC. However, he set up the Easter Tables that are still used today and also allowed for a leap year every fourth year in a year divisible by four.

Pope Gregory XIII refined the calendar in October 1582 and he made December 31 the end of the year and January 1 the beginning which was not done universally at that time. The British Empire adopted the Gregorian Calendar in 1752 adding 11 days and moving up the year for all dates between January 1 and March 31, 1751. This changed the birthdates of Benjamin Franklin and George Washington from January 6, 1705 (Old Style) to January 17, 1706 (New Style) and from February 11, 1731 (O.S.) to February 22, 1732 (N.S.). This made 1751 a short year with only 282 days. However, in Great Britain the tax year remained March 25 (Old Style) until 1800 when it was changed to April 5 (New Style).

You can find additional information about Dionysius and the Gregorian Calendar at Thank you to my son, Andy, who called this interesting information to my attention.

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