The solstice comes tomorrow, Saturday December 21, at 9:19 by Universal Time.
What is the solstitium, the “Sun-standing”? It is the moment when Earth’s north pole is most tilted away from the Sun. So it is the midpoint of winter for our northern hemisphere, of summer for the south.
The Sun does not “stands still” in its journey along its path the ecliptic, but reaches the southernmost point in that path, and makes its southermost daily acr across the sky.
Though a solstice is an instant in time, it may seem to lasts over a span of time, said to be about 5 days: over that time you don’t discern a difference in the noon height of the Sun.
Here is one of the illustrations from the “Sun, Earth, and Sesons” section, on page 85 of the Astronomical Calendar.
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This weblog maintains its right to be about astronomy or anything under the sun.
I’m confused: Does the description above: “….but reaches the northernmost point in that path, and makes its northernmost daily arc across the sky….” describe the Summer Solstice, whereas tomorrow is the Winter Solstice?
You’re right. Wording inherited from somewhere else, now corrected.
The main reason that Christians celebrate Christmas right after the solstice is because daylight is increasing, alluding to the light of Jesus which began with His birth. (Jesus described Himself as the light of the world several times, the most familiar being, “I am the light of the world. Whoever follows me will not walk in darkness, but will have the light of life.”)
“Northernmost”?
Throughout the year the Sun’s rising and setting points move north and south over the eastern and western horizons. But for a few days around each solstice the Sun rises at the same point on the eastern horizon and sets at the same point on the western horizon. I think this “standing still” was easier for our ancestors to notice and measure (e.g. with standing stones like Stonehenge) than the the noon Sun’s height.
Having said that, I’m on my way outside to measure the noon Sun’s height with my sextant. Noon tomorrow will be a couple of hours closer to the solstice than noon today, but the weather is only partly cloudy today and should be overcast and rainy tomorrow.
Yuletide blessings to one and all. May we all find hope in the dark and practice abundant openhearted kindness and charity.
Here in 35S South Africa, the noon sun arcs high in the sky. I marvel that in 6 months, the same sky minus the Sun and plus the heart of the Milky Way will be my nighttime view around New Moon. Quite a magical journey.
“What is the *solstitium*, the ‘Sun-standing’?”
Why, it’s the moment the first derivative of the Sun’s motion across latitude, versus time, is zero.
And the *aequnoctium* is the moment the second derivative of the Sun’s motion across latitude, versus time, is zero.
The Ancients understood this.
Cheers.
Here’s to 2025!