There is a season; turn, turn, turn

I posted my first picture a year ago (tomorrow) with a sunset, so I thought it would balance the universe if my 365th is a sunrise. There will not be may sunny pictures posted from central England today; this brief flash at dawn was the last we saw of it, and it has rained heavily all day

I began the year by setting the tone for what was to come: with an egegious error about it being the equinox. In fact the 2022 and 2023 equinoxes were/are on the 23rd, but the subsequent two years will be on the 22nd. Abashed by my mistake and ignorance, I spent a bit of time trying to get my head around it

Technically, the equinox is the day - in fact the instant of time - when the line of the earth's axis is exactly at right angles to the line between the centre of the sun and the centre of the earth. At that instant, the point on the equator that is at 'noon' will have the sun appearing directly overhead

"Too complicated", you will say. 'Equinox' means 'equal night'; it's the day on which we all get 12 hours day and 12 hours night. Not true. There are 12h 10m daylight here on the 23rd; only on the 26th does the daylength drop below 12h. I think that is because the sun is so big that we get the light from one edge before the centre-point has risen, and light from the trailing edge after the centre is below the horizon. Also, the earth's atmosphere bends light, giving us some daylight before the sun is physically 'up' and some after it has, in reality, gone 'down'

Even weirder, there are four days or so around the equinox when the sun does not set at either pole. The sunset at one pole, after six months of continuous daylight ('midnight sun') occurs about four days after the sunrise at the other pole for its six-month turn. That strange, unintuitive overlap must be beginning just about now. It brings to mind the 'box' in a relay race where one runner offers the baton to the next. To my friends in the southern hemisphere, we hereby offer you custody of the sun - you have four days to grab it