when to celebrate my birthday (or yours)

The standard day to celebrate your birthday (or, more accurately, “the anniversary of your birth”) is on the day which has the same calendar date (i.e. month and day) as the day that you were born.

For example, I was born on May 4th 1973, according to the currently accepted Gregorian calendar, which means that by our standard cultural traditions I just recently celebrated my 39th birthday, on May 4th 2012.

However, this isn’t the only way that one can determine the anniversaries of special events. As many of you know, Easter is a holiday that appears on a different calendar date each year.  This year (2012) it was April 8th. Last year (2011) it was April 24th. The year before that (2010) it was April 4th.


The reason Easter moves around is that Christians determine the anniversary of the resurrection of Jesus based on natural seasonal and celestial events rather than the calendar date. This adds a kind of power and authenticity to the tradition, in my opinion.  After all, calendars can change, cultures can add days or even change the names of months. So to make sure that people will always be able to figure out when Easter is, even if they live 10,000 years in the future and the calendar and names of the months have completely changed, they will still be able to do it.

The rule for Easter is this: Easter falls on the first Sunday after the first full moon after the vernal equinox.

Because the relative timing of these different natural events changes year after year, the date of Easter changes.

Neat, huh?

But it makes me think… why shouldn’t I celebrate my birthday the same way?

Looking back at some old almanac data, I have determined that the day that I was born (May 4, 1973) happened to be two days after the second new moon after the vernal equinox that year.

So why can’t that be how the day of my “birthday celebration” is defined?

If Greg Stevens’ birthday is officially defined as two days after the second new moon after the vernal equinox, then following table shows the dates of my birthday for recent and upcoming years:

Year Greg’s Birthday
2010 May 16th
2011 May 5th
2012 April 23rd
2013 May 12th
2014 May 1

So there you have it. Please keep this in mind for the future.

Oh, and to all of you who were thoughtful enough to send cards for my birthday this year:

You were late. Don’t let it happen again.


Lunar Calendar