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

This morning was the latest sunrise of the year for those of us well into the northern hemisphere, although the Sun itself was hidden by cloud and rain.

Sunrise will take place earlier each morning from now until June.

The earliest sunset was on 13th December. The shortest day was the 22nd. There were 4 minutes more daylight today than at the solstice where I am.

The year has turned.

#LatestSunrise

This morning was the latest sunrise of the year for those of us in the northern hemisphere. Sunrise will take place earlier each morning from now until June.

The earliest sunset was on 13th December. The shortest day was the 21st. There were 4 minutes more daylight today than at the solstice.

#LatestSunrise