American clocks have to be twisted forward an hour on Sunday March 12. At 2 AM, by law! – so you do it this evening, Saturday. From then till November 5, clocks have to grin and bear it, showing the false “Daylight Saving Time” in which natural 12 noon, when the Sun is highest, is called “1 PM.” Much more about this nuisance is in my page on “Clock shifting times.”
Time isn’t really shifting or being saved, but the Sun is gradually rising earlier and setting later. By how much? I’ve written myself a program. Here, for latitude 40 north, are times of sunrise; the last column is the difference in minutes from the day before, negative meaning earlier.
2023 Jan 1 7:21.8 0.00
2023 Jan 11 7:21.3 -0.22
2023 Jan 21 7:17.2 -0.57
2023 Jan 31 7: 9.7 -0.88
2023 Feb 1 7: 8.8 -0.91
2023 Feb 11 6:58.2 -1.17
2023 Feb 21 6:45.4 -1.37
2023 Mar 1 6:33.9 -1.48
2023 Mar 11 6:18.5 -1.58
2023 Mar 21 6: 2.4 -1.62
2023 Mar 31 5:46.2 -1.61
2023 Apr 1 5:44.6 -1.61
2023 Apr 11 5:28.9 -1.54
2023 Apr 21 5:14.0 -1.43
2023 May 1 5: 0.6 -1.26
2023 May 11 4:49.1 -1.05
2023 May 21 4:40.0 -0.78
2023 May 31 4:33.9 -0.48
2023 Jun 1 4:33.4 -0.45
2023 Jun 11 4:30.7 -0.12
2023 Jun 21 4:31.2 0.19
2023 Jul 1 4:34.7 0.46
2023 Jul 11 4:40.6 0.68
2023 Jul 21 4:48.3 0.83
2023 Jul 31 4:57.1 0.91
Latest sunrise was on Jan. 5; it started getting earlier, at first slowly, and will be fastest – by more than 1.6 minutes a day – around the equinox of March 20. It will be earliest on June 14, and then start gradually getting later.
I could run this table for other spans of time and other latitudes; and should widen it to show figures for sunset, and for the length of daylight. Several-dimensions reprogramming, and I’m tired of it for now and want to get on with my poster of the five escaping spacecraft.
Whatever the clock says, days get shorter as I get older.
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Guy thank you for the reference to your AC 2023 ~ I checked it out, and actually in that book, you refer back to your website LOL. I didn’t realize you have an entire page on this site dedicated to the Equation of Time, on which you clearly explain the situation in the paragraph starting with “But the larger reason is Earth’s obliquity:” I retract my earlier claim that this phenomenon cannot be explained by words alone LOL!
Your discussion of the Sun rising times made me think of the analemma and the relationship of (i) Earth’s axial tilt and (ii) orbital eccentricity to the figure 8 of the analemma. Many years ago I read the explanation that Earth’s tilt gives rise to the figure 8 pattern, whereas the eccentricity just makes the two lobes of the 8 uneven (something that the ancient Greeks apparently completely understood). I tried to find that same explanation because it included a nice animation that showed the relationship of the average daily movement of the Earth around the Sun compared to the extra time required to make that up each day since sometimes (at equinoxes) our daily rotation is reduced by the cosine of 23.5 degrees, however I could not find that particular animation.
What I did find, however, was multiple websites that offered very clear, simple explanations of the analemma that were also *completely wrong* !! They attributed the up – down motion of the Sun to axial tilt and the back-and-forth (figure 8) motion to eccentricity, in some cases including an animation that “explained” the figure 8 by showing that Earth starts speeding up near the June solstice all the way to the December solstice, not realizing that it is just blind luck that Earth’s perihelion and aphelion *happen* to line up near the solstices.
Another explanation I read was probably correct, however it was just a long paragraph of text, and I cannot imagine a less suitable topic for thorough understanding using only text (i.e., without a diagram or animation :)
The geometry is not easy to grasp. Related is the equation of time; see my attempt to explain that, on page 87 of Astronomical Calendar 2023.
I’ve written a paragraph on “analemma” for the projected new edition of Albedo to Zodiac.
We finish daylight saving on Sunday 2 April. Only three weeks to go. I can’t wait.
England does it’s clock change on the last Sunday of March at 0200 and I think that is easier to remember if you are going to do it rather than somewhere mid-month although I think it’d be better to either stay on winter or summer time all year can’t decide which but I suppose as solar noon time winter time is more natural.
Amen brother, what a damned nuisance. Thank you for the day length delta