Long day
The week either side of the solstice, when the light stops changing.
The solstice was Monday, at three minutes past four in the morning, which is a strange time for a year to turn over. Nobody was awake for it. I found out afterwards, the way you find out about most astronomical events, by reading a number.
What it looks like on the ground is this: the sun goes down around twenty to nine and it isn’t properly dark until well past nine, and in between there’s a long slow blue hour where everything looks slightly more significant than it is. Fourteen and three-quarter hours of daylight, give or take. In June we get nine and a half.
The pohutukawa are doing their thing, which they’ve timed as usual for the fortnight when everyone is too busy to look at them properly.
The word is solstice, from sol and sistere - the sun stands still. Which sounds like poetic licence and isn’t. Through most of the year the point on the horizon where the sun comes up shifts noticeably day to day. Around now it barely moves. Day length changes by a few seconds instead of a couple of minutes, and it does that for a week or so either side, so if you’re standing in it you cannot tell which day is the longest one. The date is a calculation, not an observation. You’d have to be very patient and very well equipped to find it by watching, and people were, and did.
Something else I only got straight this year: the longest day isn’t the day with the latest sunset. The earliest sunrise was a couple of weeks ago and the latest sunset is still to come, some time around New Year. The two don’t line up, because our clocks run on an averaged day while the actual sun runs a little fast or slow depending on where Earth is in its slightly-elliptical orbit and how the tilt is presenting. The discrepancy has a name and a graph, and the upshot is that the solstice sits somewhere in the middle of a longer, lopsided arrangement rather than at a clean peak.
I like that. The thing we mark as the turning point isn’t quite the turning point of anything you can see. It’s the turning point of an abstraction we agreed on.
The reason I’ve been thinking about day length rather than temperature is that the organisms I work on are counting it.
Not just responding to light being on or off, which is the obvious thing and would be enough of a trick on its own. There’s work from this year suggesting that the internal rhythms of marine phytoplankton run differently depending on how long the day is - that the whole shape of the daily molecular cycle shifts with photoperiod rather than just stretching to fit. Which means something out there in the water has, in some functional sense, noticed that the days are long now, and is behaving as though the information matters.
How much of that is anticipation and how much is response, I don’t know. I’d like to. It’s the sort of question that sounds like it should already have an answer.
Anyway. Twenty to nine, and still perfectly possible to be outside without deciding to be. From here the days get shorter, by a few seconds at first, and then in a fortnight you can feel it.