This year, we will celebrate the earliest Easter of our lifetimes. Easter hasn't fallen on March 23 since 1913, and it won't again until 2160.

I don't know about you, but I won't be around then.

Interestingly, in three years, we will have the latest Easter those of us born after 1943 have ever experienced — on April 24.

Have you ever wondered who sets the date for Easter, the holiday hardest to anticipate? Most of us just wait to see it appear on our calendars before we plan anything. I have a friend who seemed to think it was determined by the school board, and she was mad at the board when Easter break was put so early that it snowed on her while camping that weekend.

The date of Easter actually is determined by the sun and the moon, and some rules put in place at the Nicene Council in A.D. 325. So, all that resentment was wasted.

The council decided Easter will occur on the first Sunday after the first full moon after the vernal equinox (first day of spring). It can fall anywhere between March 22 and April 25. But the calendar is not equitable about when Easter falls. You may be surprised to see just how random it is.

The most common date for Easter is not in April, but rather March 31. Easter occurs on that day 24 times between 1753, the first year America adopted the Gregorian calendar, and 500 years from then, or 2252. The second most common is April 16 (23 times), and April 11, the date I always think sounds most like Easter, is third (22 times).

I became interested in this one Easter Sunday when I remembered that my grandmother had been born on April 13, and I wondered how many times in her life her birthday had fallen on Easter. Out of curiosity, I looked it up.

Answer: zero.

When her birthday fell on Sunday — an occurrence of 10-12 times in the average lifetime — it was never Easter Sunday. My grandmother had a short life — her birthday only fell on Sunday six times. The year before she was born, April 13 was Easter Sunday.

My friend Sherryl celebrates her birthday on March 24. When I told her Easter could occur as early as March 22, her ears perked up. When would Easter fall on her birthday, she wanted to know?

Never, I had to tell her. Since the change to the Gregorian calendar, March 24 has only been Easter Sunday twice — in 1799 and 1940. Between now and 2252 (I had to stop somewhere), it will not happen again. March 22 is even worse. It hasn't been Easter since 1818 and won't be again, in my calculations.

There really is no fairness to it. Last year, Easter fell on April 8. That date hadn't been Easter since 1928, but will be again in 2012, just four years from now. My niece Amy has a birthday on April 23, the sixth least-common Easter date. Yet, she was 19 when the two events were paired together.

My nephew Richard was born on April 24, the fourth least-common date for Easter. He will get his birthday on Easter once, at age 31. Unless, of course, he lives to be 115. Nephew Mike, born on March 25, will celebrate Easter birthdays when he is 48 and 59. Interestingly, his cousin Tom, born on March 26, which has twice as many Easter occurrences as does March 25, will not get Easter birthdays until he is 68, 79 and 90. Another nephew, Zach, hit the mother lode with Easter birthdays, occurring as he turns 1, 12, 23, 85 and 96.

When you think about the criteria, it does make sense that the soonest possible and latest possible dates for Easter would be less common than the ones in the middle, but there still appears to be quite a bit of randomness.

While this year's Easter is the earliest we will ever see, the latest will occur in 2038, on April 25. Those of you who do not expect to be around in 2038 may have been here in 1943, the last time Easter fell on that latest possible date.

Next year, Easter will fall on April 12, the fourth most-common date in the 500 years I mapped out, and the second most common date for Easter in the 1900s and 2000s.

Now you know that bit of information ahead of the school board.

Janean Justham is a mother of seven living in Salt Lake City.