Talk:Day

Relevance of the picture of the Bay of Naples

I question the validity of singling out that shot as relevant to the entry. I read through for any mention to the city or the bay itself and since there was none, I suggest its removal as irrelevant. Maringaense 00:13, 29 September 2018 (UTC) — Preceding unsigned comment added by Maringaense (talk • contribs)

A Commons file used on this page or its Wikidata item has been nominated for deletion

The following Wikimedia Commons file used on this page or its Wikidata item has been nominated for deletion:

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Participate in the deletion discussion at the nomination page. —Community Tech bot (talk) 22:39, 7 January 2022 (UTC)

How could we expand on this article?

PerfectSoundWhatever, this is a really difficult and amorphous topic to expand upon. What should we do first? CactiStaccingCrane (talk) 11:37, 19 August 2022 (UTC)

We should increase citation density, which will increase the amount of bytes. For example, the section Apparent and mean solar day could use a rewrite with more citations. Leap seconds is entirely unsourced. The longitudal change thing is super interesting, we could have some prose to go along with that table. I could attempt to try to translate some of that paper, not sure how that will go, but it'd be a better idea to find other sources about the subject (and make sure that it actually is a thing). For new sections? Maybe parts of the day and their cultural implications could be added. No parts of the day article exists anywhere on wiki afaik. — PerfectSoundWhatever (t; c) 13:29, 19 August 2022 (UTC)

I agree, let's do it then :) CactiStaccingCrane (talk) 13:31, 19 August 2022 (UTC)

"The Earth-Moon system is not in the Hubble flow"

@Thucydides411: do you have a source that disproves that the Earth-Moon system is not impacted by the expansion of the Universe, as stated in this source? I am far from an expert in the subject matter, so my only way to research is to go off of papers that I can find, so sorry if the statement is incorrect. But I'd like to see proof before removing the statement entirely, thanks! — PerfectSoundWhatever (t; c) 16:02, 22 August 2022 (UTC)

@PerfectSoundWhatever: Hubble's law (of expansion of the universe) only applies on large scales - far larger than the scale of a galaxy, not to mention the Solar System. The "Hubble flow" is a term for the distant universe, where expansion begins to take effect. At smaller scales, gravitational interactions between stars, planets, etc. dominate, and the Universe isn't homogeneous, so the assumptions of cosmological theory don't even hold. Cosmology describes what happens on very large scales, not on the scale of the Solar System, or even of the Milky Way.

Any basic text on cosmology will cover this, but I'll link to a review article on the Hubble constant here. You can see that it discusses the "Hubble flow", and the fact that it only begins at approximately Megaparsec scales (i.e., many orders of magnitude larger than the distance between the Earth and Moon).

If you're not satisfied with this source, my one plea is not to re-add the claim about the distance to the Moon being affected by cosmic expansion unless you can find much better sourcing than what was previously used (and I'm fairly confident you won't find better sourcing, because the claim is incorrect). -Thucydides411 (talk) 08:54, 23 August 2022 (UTC)

Since the expansion of the universe is now supposed to be caused by the cosmological constant it applies at all scales. Perhaps the previous section means to say that it has no measurable effect on the small scales mentioned.−Woodstone (talk) 16:18, 23 August 2022 (UTC)

Thank you for the detailed reply, @Thucydides411:. This level of study really goes over my head. I found a discussion in the comments of the first answer here and looked at some of the linked papers.This paper seems to say that Hubble expansion affects the Moon-Earth system. Could you please verify if this is correct? Another paper linked states "The effect on the orbit is insignificant as are the effects on the galactic and galactic--cluster scales". I am quite confused as to whether there is a scientific consensus on the topic. It appears muddled, so of course, the statement should be left out for now. Just wanted to additionally send those papers. — PerfectSoundWhatever (t; c) 19:39, 23 August 2022 (UTC)

@Woodstone: The cosmological constant is one hypothesis for the cause of the expansion, but there are also different hypothesized forms of dark energy. The cosmological model assumes a homogeneous matter distribution and constant spatial curvature, neither of which is satisfied on small scales (below a few Megaparsecs). The cosmological model only applies on scales many orders of magnitude larger than the Solar System, so it's meaningless to talk about cosmic expansion inside the Solar System. In any case, I think this sort of speculation is esoteric enough that it should not be included in this article. -Thucydides411 (talk) 18:31, 24 August 2022 (UTC)

Agreed that it does not make sense to mention expansion of the universe as influencing length of day here. However saying categorically that it does not apply on certain scales makes no sense either. Natural laws are universal. Effects of them may not be measurable (relevant) on certain scales.−Woodstone (talk) 08:32, 25 August 2022 (UTC)

My point is that the standard cosmological model doesn't not apply at all on the scale of the Solar System. It assumes a homogenous distribution of matter and constant spatial curvature. Neither of those conditions is met in the Solar System. -Thucydides411 (talk) 12:10, 25 August 2022 (UTC)

Names?

Suggestion:

shouldn't the names of each day of the week be mentioned here somewhere? Maybe a link the article Names of the days of the week. 94.252.6.224 (talk) 19:28, 18 October 2023 (UTC)

Revert

I reverted this edit because the article is Day, not Earth's rotation. The previous pictures were a better illustration of the concept than a picture of the Earth spinning. Note in particular that the face of the Earth in the animation is fully lit, so it does not even illustrate how the day/night cycle arises. Srleffler (talk) 01:09, 30 October 2023 (UTC)

Bad link in references

For reference 21, clicking on "The Length of the Day: A Cosmological Perspective" takes you to a gambling website. MikePhysics (talk) 21:01, 25 May 2025 (UTC)

Fixed. Thanks for letting us know.--Srleffler (talk) 07:16, 26 May 2025 (UTC)

Solution

I've updated the Day page, classifying the times of day according to common consensus: morning (sunrise until noon), afternoon (noon until sunset) and evening (sunset until midnight). In the period between midnight until sunrise, I put a question mark, as I could not find a specific term for this period. 168.232.221.42 (talk) 16:33, 23 June 2025 (UTC)

If anyone knows of a term to describe the period between midnight until sunrise, could you add it to the table? 168.232.221.42 (talk) 16:35, 23 June 2025 (UTC)

I don't believe there is any such term in common use. I also don't agree that "evening" means "sunset until midnight". As noted at Evening, some definitions of the term consider evening to begin before sunset, particularly in the summer. The OED defines it essentially as 6 pm or sunset, whichever is earlier, which sounds about right to me. It also doesn't extend to midnight. As indicated in this article, evening ends when one goes to bed (and the article cites sources to support this).

On Wikipedia, everything in the articles must be verifiable by reference to reliable published sources. You cannot remove material that is supported by references to sources and replace it with your own contrary opinion, supported by nothing. That is just not how Wikipedia works.--Srleffler (talk) 00:35, 24 June 2025 (UTC)

Table

I'm moving the table here for further discussion:

Period	Definition	Part of the day
?	Midnight until sunrise	Night
Morning	Sunrise until noon	Daytime
Afternoon	Noon until sunset
Evening	Sunset until midnight	Night

I notice that the table cites three sources for the definition of "evening", all of which flatly contradict the definition given in the table. This is not OK. We rely on sources, not editors' own opinions or original research. The sources also indicate the resolution to the question mark: "evening" ends when you go to bed. The time between when you go to bed and sunrise is night.--Srleffler (talk) 00:43, 24 June 2025 (UTC)

The right thing to do would be to differentiate the 4 periods/parts of the day based on times (o'clock) and not on how the sky is. I don't think it's right to differentiate the periods/parts with sunrise and sunset, especially because there are days when the sky will be cloudy (completely covered in clouds), and even with fog, snow or rain. And since the day has 24 hours, the fair reasoning would be that each part/period would have 6 hours each: ? (00:00 until 05:59), morning (06:00 until 11:59), afternoon (12:00 until 17:59) and evening/night (18:00 until 23:59). Remembering that I wrote the time in the 24-hour clock system, I do not use the 12-hour clock (AM and PM) system. The differences between evening and night are very confusing, and I think it's right to treat them as synonyms. But anyway, I'm here to hear other positions on the topic. 168.232.221.124 (talk) 15:11, 26 June 2025 (UTC)

I'm not sure whether you're serious or just trolling here. That's not how the terms are defined, and it really doesn't matter whether you think it's "right" to define them a particular way. "Fair reasoning" is irrelevant.

More fundamentally, on Wikipedia content is determined by what reliable sources say, not based on the opinions or reasoning of individual editors. --Srleffler (talk) 04:32, 27 June 2025 (UTC)

@Srleffler In the country where I live, which is Brazil, the 4 periods of the day are divided into 6 hours each.

In these cited sources, they prove that the division of the periods of the day is like this in Brazil: madrugada ("unnamed period", 00:00 until 05:59), manhã (morning, 06:00 until 11:59), tarde (afternoon, 12:00 until 17:59) and noite (evening or night, 18:00 until 23:59).

But that's okay, I know that the periods of the day vary according to the country. I just mentioned that dividing the day into 4 periods of 6 hours would be correct, according to the external sources that I presented. 168.232.221.110 (talk) 12:12, 27 June 2025 (UTC)

That's interesting. We don't do that in English, at least not in any English-speaking country I'm familiar with. We can add to the article a discussion of how other cultures and languages deal with divisions of the day. We just shouldn't try to force-fit English usage into following the Brazilian custom.--Srleffler (talk) 17:34, 28 June 2025 (UTC)

By the way, we do have a term for the period between midnight and dawn. It is "early morning". --Srleffler (talk) 17:43, 28 June 2025 (UTC)

I added a section on the Brazilian division of the day to the article. Thanks for explaining it, and for providing references!--Srleffler (talk) 17:58, 28 June 2025 (UTC)

@Srleffler Thank you for placing the table on page. About the period from midnight until sunrise, I agree it is called "wee hours". After a long time reflecting and thinking a lot. In fact, there are sources that prove that "wee hours" is valid. 168.232.221.165 (talk) 03:20, 4 July 2025 (UTC)

Yes, "wee hours" also works, although it is kind of informal. One could also say the wee hours of the morning, which is the origin of the term.--Srleffler (talk) 16:32, 4 July 2025 (UTC)

Brazil's way of dividing up the day makes a lot more sense there than it would in much of the English-speaking world. Looking at a sunrise/sunset list for Brasilia, it looks like sunrise varies between about 5:30 and 6:40 am throughout the year, while sunset varies between 5:50 and 6:50 pm. Standardizing the names of the parts of the day with transitions at 6 am, noon, and 6 pm would work well there. In Vancouver, on the other hand, the sun sets around 4:15 pm in December and 9:20 pm in June. It would be very strange to call 5:00 "afternoon" when the sun has been down for almost an hour, and even stranger to call 8:00 pm "night" when it is still full daylight. The English term "evening" covers a lot of this variability, referring to a part of the day that is defined more by what you do at that time of day than by whether it is light or dark out.--Srleffler (talk) 01:11, 8 July 2025 (UTC)

@Srleffler In the country (Brazil) where I live, the day is actually divided into four periods, and I think that's correct. As I said, dawn/sunrise and sunset/dusk don't have fixed times and vary according to the seasons, especially here. Here in winter (June or July), the sun rises at 6:50 and sets around 17:40, and dawn occurs at 6:20 and dusk at 18:05. In summer (December), the sun rises at 5:15 and sets at 18:58, and dawn occurs at 4:30 and dusk at 19:20. I find it interesting to see places where the sun rises at 4:40 and sets at 21:20. I always consider valid periods based on the times presented by the source. One thing I find super interesting is that in the summer here, the sun shines entire morning and entire afternoon, and late wee hours and early evening/night.

Here in Brazil, we consider evening and night as synonyms. In other words, in the summer, here in Brazil, the sun shines in four periods. As we know, historically, the moon is used as a symbol of evening/night and wee hours, but sometimes it appears in the morning and afternoon as well. But the stars only appear in the evening/night and wee hours. I would think it would be really cool to see the sun rise at 3:10 and set at 21:30, but it's a shame that won't happen here in Brazil. 168.232.221.196 (talk) 01:44, 11 July 2025 (UTC)

In the summer, when the sun is already shining at 5:15, I still consider it wee hours. And when the sun continues shining after 18:00, I already consider it night. 168.232.221.196 (talk) 01:56, 11 July 2025 (UTC)

Here in Brazil, we consider wee hours and morning as different periods. 168.232.221.196 (talk) 12:38, 11 July 2025 (UTC)

References

Brazilian churn

What is it with the little table of parts of the day in Brazil? Never has such a small part of an article caused such relentless churn. Endless changes from one time format to another, to another. Attempts to translate the terms into English for no particular reason. And on, and on, and on. -- Srleffler (talk) 05:15, 29 May 2026 (UTC)

As far as is discernable, it's all a result of one obsessed person in Brazil who can't let go of the notion that this needs to be litigated. The page was protected for a while, but that expired a few days ago, so the disruption may arise again. However, page protection can always be resumed. cheers, anastrophe, an editor he is. 06:58, 29 May 2026 (UTC)

Given how simple the presented information is (four six-hour periods in sequence), I don't think there's any need for it to be a full table. I've rewritten it as a sentence. Belbury (talk) 08:15, 29 May 2026 (UTC)

Nicely done, thank you. cheers, anastrophe, an editor he is. 17:53, 29 May 2026 (UTC)