Talk:Solar time

The chart table appears wrong, citing seconds while the graph shows minutes

The chart shows the annual solar day deviating by seconds (+ or - 15 or seconds). The sinusoidal graph shows the solar days deviating by approximately the same numbers, but they are labeled minutes which seems much more accurate. — Preceding unsigned comment added by 50.53.39.108 (talk) 18:12, 12 January 2021 (UTC)

There's nothing obviously wrong with the chart or graph. The chart is describing how short or long each day is at different times of year. The graph shows how much difference has accumulated because of the length of each day. Jc3s5h (talk) 18:35, 12 January 2021 (UTC)

Solar time association & Solar time calculator

There is a website from the solar time association with a easy worldwide solar time calculator: Solar time calculator. — Preceding unsigned comment added by 77.191.87.174 (talk) 17:15, 7 May 2022 (UTC)

Star clocks

@Jc3s5h: The old page said "star clock". My edit did nothing to change this - it simply moved the link to the first mention. If you have an objection to the term "star clock", you should actually fix the article, not spam reverts. --Mathnerd314159 (talk) 23:28, 3 June 2022 (UTC)

According to Chicago Manual of Style 17th ed. ¶ 7.57, "scare quotes" "are often used to alert readers that a tem is used in a nonstandard (or slang), ironic, or other special sense. In this article "star time" is used as a nonstandard term for the methods used by astronomers to keep time before the availability of atomic clocks. A description of these methods may be found in chapter 3, "Systems of Time Measurement" and chapter 15, "The Distribution of Time", in Explanatory Supplement to the Astronomical Ephemeris and The American Ephemeris and Nautical Almanac (London: Her Majesty's Stationery Office, 1961).

By removing the quote marks and linking to the star clock Wikipedia article you changed the meaning to a method that is just a rough approximation, suitable for use by people who's watch batteries have become fully discharged. Jc3s5h (talk) 10:18, 4 June 2022 (UTC)

The methods described in the book are (ch 3) universal time, sidereal time, and ephemeris time. Of these sidereal time is clearly the one meant by "star time"; it is determined by observing the positions of various stars and comparing with a star catalogue. The method described in star clock is a simplified instance of this method, using a single naked eye observation of the Big Dipper. It's true that there are more accurate methods for determining sidereal time, as discussed in the sidereal time article, but the sentence clarifies that we are talking about methods before "the beginning of the 20th century". Zenith telescopes were rare before 1900 (the earliest drawing there is from 1898), so I think this "rough approximation" star clock method was the main method of determining sidereal time in that era. Hence it seems appropriate to link to the article on the subject. Also MOS:SCAREQUOTES says to avoid scare quotes if possible. Mathnerd314159 (talk) 21:10, 4 June 2022 (UTC)

I don't know about zenith telescopes in general, but agree the photographic zenith tube wasn't used until the 20th century. But the meridian circle could achieve nearly the same accuracy, and that was in use through most of the 19th century. A graph on page 145 of McCarthy & Seidelmann shows steady improvement in optical instrument time measurement accuracy throughout the 19th century, achieving an accuracy of a few milliseconds per day by the end of the century. The performance of optical instruments became limited by the irregularities in Earth rotation about 1920, as best I can read the values off the graph, at about 0.8 millisecond per day.

As for scare quotes, perhaps there is a more elegant way to phrase the section. But MOS:SCAREQUOTES seem to be more about implying something improper is going on without making a direct accusation, such as "Mr. Jones checked into the motel with his 'wife'." It can be difficult to find an accurate term for a concept that the reader will understand in the first few sentences of an explanation. Jc3s5h (talk) 22:33, 4 June 2022 (UTC)

Well, I realized the article was wildly inaccurate in attributing mean solar time to Babylonia. So I rewrote that, and removed "star clocks" entirely. Feel free to improve. Mathnerd314159 (talk) 03:42, 6 June 2022 (UTC)

Semi-protected edit request on 13 August 2022

In the 3rd paragraph of the Introduction. The "Currently, {{When...}} a mean solar day is about ..." tag can be edited to:

As of 2008, a mean solar day is about 86,400.002 SI seconds.

Which is referenced in the footnoted source (Leap Seconds from USNO) already at the end of the sentence. At approximately a millisecond per century, it is infrequent enough for manual editing. 156.57.155.13 (talk) 00:06, 14 August 2022 (UTC)

 Done —Sirdog (talk) 07:21, 14 August 2022 (UTC)

Semi-protected edit request on 23 August 2022

There is a syntax error on this page. At te end of the body, it has a reference like this:

<<ref name="time-from-earth-rotation-to-atomic-physics" />

Note the double < at the start. It shows up on the page. Teunduynstee (talk) 14:55, 23 August 2022 (UTC)

 Done ScottishFinnishRadish (talk) 15:13, 23 August 2022 (UTC)

Semi-protected edit request on 29 December 2022

2600:1700:8B90:B70:B87A:5538:F385:869A (talk) 05:42, 29 December 2022 (UTC)

§ Signs Of The Reicipie Of Arnokue

 Not done: it's not clear what changes you want to be made. Please mention the specific changes in a "change X to Y" format and provide a reliable source if appropriate. Cannolis (talk) 06:24, 29 December 2022 (UTC)

Proposal: Move mean solar time stuff to Universal Time and rename to Apparent solar time

The article is currently about two topics, apparent solar time and mean solar time. These don't really have much in common other than the name. I think when people talk about "solar time" they are thinking of apparent solar time, so making solar time a redirect to apparent solar time or a disambiguation seems justified. Mean solar time is basically UT1, and could be added as a note to the history section there. Opinions before I make a formal move request? Mathnerd314159 (talk) 04:49, 3 January 2023 (UTC)

There's an important difference between mean solar time and universal time. The former can be calculated for any longitude. Universal time is always at 0° longitude, give or take a few hundred meters. Jc3s5h (talk) 05:39, 3 January 2023 (UTC)

There is a local mean time article, which is basically a duplicate of what's in this page regarding mean solar time. So maybe that's a better place to move any remaining mean solar time details. Mathnerd314159 (talk) 16:23, 3 January 2023 (UTC)

The Earth's orbit around the Sun, showing its eccentricity

Nice representation but it has the Vernal Equinox in September rather than March. 73.212.181.150 (talk) 12:00, 5 March 2023 (UTC)

The figure is approximately correct, you just have to think about the point of view. In late March the Earth will be located in its orbit at the left hand side of the figure. If some observers on, for example, the International Space Station were to look at the Sun (located in the center if the figure) they would see the stars surrounding the Sun indicate the celestial longitude of the sun is 0°. Of course observers on the ground would not be able to see the stars because the sky is too bright. Jc3s5h (talk) 15:59, 5 March 2023 (UTC)

Right, I see it now. I had the wrong perspective; thanks. 73.212.181.150 (talk) 04:27, 6 March 2023 (UTC)

The Negative Day?

It might be interesting to add material to this article along the following lines.

The revolution of Earth around the Sun produces apparent motion of the Sun from west to east (unlike the apparent motion from east to west resulting from Earth's rotation on its axis).

After each sidereal day, the Sun appears a bit to the east relative to where it was at the beginning of that sidereal day. After a year, those bits of eastward drift each sidereal day add up to a full apparent west-to-east circuit overhead.

Since the circuit moves west to east, it opposes the dominant, east-to-west motion that produces the daily cycle that we notice. In that sense, you might refer to the west-to-east motion as a "negative day" that occurs in the course of each year.

The 365.25 days that we see each year are thus composed of 366.25 sidereal days produced by Earth's rotation on its axis plus 1 negative apparent day produced by the revolution of Earth around the Sun. Jsryanjr (talk) 16:05, 21 December 2023 (UTC)

So, something like the illustration that's now at the top of the page, with its caption? —Tamfang (talk) 04:59, 31 December 2023 (UTC)