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Are you in the dark about the shortest day?

Why is the earliest sunrise not the same date as the shortest day on the Winter Solstice?

It wasn’t until a couple of years ago that I noticed that the mornings weren’t getting any lighter despite it being after 21st December, the Winter Solstice and the shortest day of the year. Naturally, worrying that the apocalypse was imminent and no-one else had noticed, I mentioned my concern to a good friend who was well versed in science and was a fellow dawn watcher, also with animals needing pre-daylight attention in Winter.

Naturally, my friend knew all about this. The answer wasn’t an obvious one, but the fact that I have since mentioned it to several people who were equally amazed made me feel better about this lifelong knowledge gap and inspired me to share this in case others were similarly in the dark.

sheep in snow in the brecon beacons winter solstice

Put very simply, one main factor causes this – the discrepancy between solar time for a day (the time it takes the earth to perform a rotation) and clock time which is calculated as the same 24 hours every day of the year using the Gregorian Calendar which has been universally adopted. The tilt of the earth’s axis means we are orbiting around the sun in an elliptical or oblong fashion rather than a purely round way.

As solar time and clock time are not exactly the same, this has the effect that in the mid-Northern hemisphere the earliest sunset will be in early December, before the Winter Solstice, and the latest sunrise will be early January. This depends on your latitude, but here in the Brecon Beacons this morning, January 2nd 2022, was the latest sunrise at 08.21am hoorah, so looking forwards to lighter mornings from now on!

Julia – Good Day Out

blondie the rescue horse looking at the dawn in winter

For more detailed explanations and science as well as learning about the oddities of Solar Noon, do pop to the fascinating Time & Date website as well as Earth Sky     Pop to Metcheck for easy to find weather and sunrise / sunset times.

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