You thought today was the first day of spring?  Maybe in America, but not here.  In Ireland, the first day of spring is the 1st of February. 

I was a little skeptical myself when Amy came home from work one day and announced that she had been told that 1 February was the first day of spring.  How could that be?  You can’t just make up something like that, because spring begins on the vernal equinox, when the Earth’s axis shifts so that the Sun passes directly over the equator on its way north, and that usually happens around the 20th of March (sometimes the 21st) .  But I looked it up, and sure enough, spring comes to Ireland on 1 February.  Summer, by the way, begins 1 May.

I began to consider just what makes a season.  For school kids, summer begins the day school lets out, and ends the day the next school year begins.  For others, Memorial Day and Labor Day mark the opening and closing of summer.  Officially, though, we were always told summer began on the longest day of the year, in June, and ended on the autumnal equinox in September.  Of course, we also were told that the seasons were reversed in the Southern Hemisphere. 

Think about this possibility (I’m sure for somebody, it’s a reality):  You and your neighbor live in an equatorial country.  The equator passes down the middle of your street, and you live on opposite sides.   By the definition of seasons used in the U.S., you celebrate the first day of spring on the day your neighbor celebrates the first day of Fall, since one of you is in the Northern Hemisphere and the other in the Southern.  Doesn’t really work, does it?  Which explains why many cultures have just two seasons, rainy and dry. 

If you look up the sunrise and sunset of a place like Singapore, which is just 90 miles north of the equator, the longest day of the year is in June and clocks in at 12 hours, 12 minutes, and a few seconds. The shortest day?  That’s in December, and it’s 12 hours, 2 minutes and some odd seconds of sunlight.  Actually, from late November to early January, for over six weeks, the amount of daylight per day never varies by more than a minute.  In other places even closer to the equator, or on it, the variation is even less.  The extremes in sunlight happen as you move farther from the equator, which explains the days with no sunrise or sunset, depending on the time of year, in places like Alaska.  Cork is around 52 degrees north, so the variation is quite large.

I thought a bit about our definitions of time, and which time units are “real” and which we just make up.  Of course, a year is not a human-made thing.  Whether people are there to observe it or not, it takes a year for the Earth to revolve around the Sun.  A day, too, has an obvious significance.  But a week?  It may be Biblical, but it doesn’t have any astronomical significance.  The same with a month (unless we’re talking about a lunar month).  Hours, minutes, all made up to help us make sense of the passage of time.  The seasons, though, are partly man-made concepts that someone decided to tie to the very real shifting of the earth on its axis and the change in weather that follows in most places.  Yes, there is a day with the most sunshine and a day with the least, and there are two days (the equinoxes) when the sun is over the equator.  But why should those necessarily define the seasons?  In most cultures, they don’t.  A summer that begins on 1 May and ends on 31 July encompasses most (but not quite all) of the days with the most sunshine.  It may seem different to an American to define summer that way, but it makes sense.

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