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Can You Count to 10?
, Astronomy Boy

In terms of our calendar, when does a new decade (ANY decade) begin? If you said that a decade starts with a year ending in "0," you are incorrect.

It may sound reasonable, but it's wrong. Actually, each new decade starts with a year ending in "1" and ends with a year ending in "0."

So while many people used the end of 2009 as an excuse for commemorating the end of the decade, they were all doing so a year too early.

That decade actually ended on December 31, 2010. The current decade actually ends on December 31, 2020. The next new decade begins on January 1, 2021.

This is not exactly rocket science, folks! To understand when a decade begins and ends only requires that we know how to count to 10. I don't know about you, but I learned to count to 10 a long, long time ago.

Here's how we count our years.

The calendar we use today is the Gregorian Calendar. The counting of the years in the Gregorian Calendar began with the Year 1 CE. So it's obvious that the first decade in our calendar included the years 1 through 10. Simple, no?

What about the second decade? You've probably already figured out that the second decade was the years 11 through 20. Let's list a few more decades from the beginning of our calendar and the years comprising each one.

Please note: I am fully aware that many calendar systems exist. When I speak of the Gregorian calendar as "the calendar we use today," I am referring to the fact that the Gregorian Calendar is the most commonly used civil calendar. Many cultures also utilize other calendars, primarily religious ones, but the Gregorian Calendar is the closest thing to an "official" or "universal" calendar for planet Earth.

1-10 11-20 21-30 31-40 41-50 51-60 61-70 71-20 81-90 91-100 101-110

By now, the pattern is very clear. Each decade starts with a year ending in "1." Each decade concludes with a year ending in "0."

Let's skip a few centuries and list the years of the most recent decades.

1951-1960 1961-1970 1971-1980 1981-1990 1991-2000 2001-2010 2011-2020

Hey! Look at that! The year 2010 was NOT the start of a new decade. It was, in fact, the last year of the decade that began with 2001.

Now ask yourself a question. If the above is true (and it is), why does the world's media bombard us with all sorts of "end-of-the-decade" stories toward the end of every year that ends with a "9?"

Don't they realize that the each decade continues until the end of a year ending in a "0?"

Don't they understand that ALL decades begin with a "1" and end with a "0?"

Don't they know that all of their "end-of-the-decade" stuff is always a year too early?

Can't they count to 10?

The next new decade does not start until January 1, 2021. Why this mistake is repeated decade after decade is one of life's annoying little mysteries.

It may have occurred to you that if some people have trouble counting to 10, those same people probably can't count to 100 or to 1,000 either.

And you would be correct. At the end of 1999, all the hoopla regarding the beginning of the new millennium was one year too early.

Amazingly, when confronted with the simple fact of how years are counted, many people act as if they are being asked to understand the Theory of Relativity or perhaps pilot a spacecraft to Mars. We're talking here about counting to 10, for crying out loud!

Why do so many people find it so difficult? Beats me!