The Winter Solstice 2025

Just a quick note to point out that the Winter Solstice in the Northern hemisphere happens today, Sunday 21st December 2025, at 15.03 UT (GMT).

In Dublin, sunrise yesterday (20th December) was at 8.37 am and sunset at 4.07 pm, while today the sunrise was at 8.38 am and sunset at 4.08 pm. Both sunrise and sunset happen later tomorrow than today, so the Solstice marks neither the latest sunrise nor the earliest sunset. We have to wait until January for the latest sunrise (8.40am) and the earliest sunset (4.06pm) actually happened over a week ago. The interval between the two events will, however, be about 2 seconds longer tomorrow than today; and yesterday the gap was about 4 seconds longer than today. Taking a day to be the interval between sunrise and sunset, today is the shortest.

For a full explanation of this, see this older Winter Solstice post.

#DecemberSolstice #EarliestSunset #LatestSunrise #SolarNoon #WinterSolstice

The Winter Solstice 2024

Just a quick note to point out that the Winter Solstice in the Northern hemisphere happens tomorrow, Saturday 21st December 2024, at 9.21 UT (GMT). I am posting this in advance as I am planning to have a line-in tomorrow morning.

In Dublin, sunrise today (20th December) was at 8.37 am and sunset at 4.07 pm, while tomorrow the sunrise is at 8.38 am and sunset at 4.08 pm. Notice that both sunrise and sunset happen later tomorrow than today, so the Solstice marks neither the latest sunrise nor the earliest sunset: the interval between the two events will, however, be about 2 seconds shorter tomorrow than today. For a full explanation of this, see this older Winter Solstice post.

Anyway, today is has been the last day of teaching at Maynooth University. I did my final lecture of 2024 this morning and attended project presentations this afternoon. Campus has been very quiet all day, most people having already departed for the break. That makes me feel less guilty about going home earlier than usual at 4.15pm. Now it’s time power down everything in my office for the break and head home via the shops!

#EarliestSunset #LatestSunrise #SolarNoon #WinterSolstice

Feeling the winter blues? Well, cheer up. The evenings are getting lighter already; today's sunset is 5 seconds later than yesterday's (at least, it is if you're around 52⁰N). And it only gets better from here.

#SantaLucia #EarliestSunset

Happy #EarliestSunset day! (At the latitude of Boston MA, anyway. YMMV if else-latitude.)

Gory details on why the earliest sunset isn't on the day of the winter solstice:
http://larry.denenberg.com/earliest-sunset.html

(Looks like it translates to #EarliestSunrise at the same latitude in the southern hemisphere.)