From Wikipedia, the free encyclopedia
Jump to: navigation, search
WikiProject Time (Rated Start-class, Low-importance)
WikiProject icon This article is within the scope of WikiProject Time, a collaborative effort to improve the coverage of Time on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
Start-Class article Start  This article has been rated as Start-Class on the project's quality scale.
 Low  This article has been rated as Low-importance on the project's importance scale.

WikiProject Time assessment rating comment[edit]

Want to help write or improve articles about Time? Join WikiProject Time or visit the Time Portal for a list of articles that need improving.
Yamara 08:42, 12 February 2008 (UTC)


Could someone explain why solar noon usually occurs during the early afternoon? — Knowledge Seeker 14:31, 28 Apr 2005 (UTC)

The time zone is completely irrelevant. What is relevant is that on a given day, solar noon occurs at a real time depending on the exact spot on earth, since it is defined as that time of day when the sun is a close as possible to directly overhead. But within any time zone, all clock times are identical. (Solar noon is approximately identical for all points on earth along a given longitude line.) For more information, see the section Time zone: Skewing of zones.

Revert explanation[edit]

As I understand it, since we use time zones, in most places solar noon and clock noon do not coincide, so I'm reverting back to say that. Or am I missing something? — Knowledge Seeker 08:19, 2 Jun 2005 (UTC)

When I read the sentence as it stands now, it is confusing. Perhaps it just needs to be reworded, as I had to do a double take the first time I read it. "Because" we use time-zones, that is why it doesn't match up all the time, so that is why it makes sense to state that, "Because of the use of Time Zones, the time noon and the solar noon do not always match up". I believe it should say "does not". Any other input? Noah 08:25, Jun 2, 2005 (UTC)

Here is the original sentence:

Due to the use of time zones and daylight saving time, there are few places and times where the highest point of the sun and a clock time of noon coincide.

Since we use time zones &c, there are few (=not many) places where the times coincide. To say that there are few places and times where they do not coincide would imply that they coincide in most places. — Knowledge Seeker 08:30, 2 Jun 2005 (UTC)

Nevertheless I agree with you that the sentence is confusing. I will try rewording it. — Knowledge Seeker 08:34, 2 Jun 2005 (UTC)
Ah you were right. Then perhaps we could re-word that to state... Due to the use of time zones and daylight saving time, there are many places where the highest point of the sun and the clock time of noon do not coincide. (Removed "and times" because we're talking about time zones and daylight savings, which all have to do with places, not times). Personally I think it makes more sense and is easier to read than the original sentence. What do you say? Noah 08:36, Jun 2, 2005 (UTC)
It's funny; I just reworded it to a version very similar to what you proposed. Feel free to edit it to make it clearer. I wasn't sure about the "times" thing. I thought maybe it was referring to the equation of time (that day lengths are different at different times during the year), so I changed it to "most days", but get rid of that if you want. — Knowledge Seeker 08:40, 2 Jun 2005 (UTC)
Alright, check it out and tell me if it reads clearer. I also added the "Astronomy" category to the article, since it mentions solar noon, et cetera. Also the reason solar noon occurs in the afternoon is because the article writer probably lives in the northern hemesphere where solor noon points north, which is not directly above at your apex. It would only be directly above if you are near the equator. FYI. ;) Noah 08:49, Jun 2, 2005 (UTC)
Looks good to me. Thanks for the explanation. I'll have to ponder the afternoon thing because I don't understand it yet. Do you think you could reword that so that it doesn't have a northern hemisphere bias? I would if I understood it =) — Knowledge Seeker 09:06, 2 Jun 2005 (UTC)
Alright, removed the little piece of north/south bias, and expanded on the solar noon sentence we have been discussing. :) Noah 11:36, Jun 2, 2005 (UTC)

a.m. - p.m.[edit]

"Despite this strict logic, it is common practice in the United States to designate noon as 12:00 pm." From the p.m. article. i think this should be incorperated — Preceding unsigned comment added by (talk) 21:54, 18 January 2006 (UTC)

From this article: "Most people in North America, though, assume that 12 a.m. and 12 p.m. signify noon and midnight, respectively." Not only have I never heard 12 a.m. to signify noon, and 12 p.m. to signify midnight; but this also directly contradicts the 12-hour clock article which states, "In the United States, though, especially with the preponderance of digital clocks and computers since the 1980s, noon is often called 12:00 p.m. and midnight 12:00 a.m., as at the beginning of a day." AM and PM either don't apply to midnight and noon, or midnight is AM and noon is PM, not the other way around. Onlynone 03:58, 17 October 2007 (UTC)

I think a mention of the fact that 'p.m.' is valid for times arbitrarily close to the notional "12:00", i.e. 12:00:00.0000001 should be included. --Random832 13:36, 4 December 2006 (UTC)

Removed "12:00:00.000 . . . 1" as being 12 noon, it implies an infinite number of zeroes and is incorrect -- (talk) 04:40, 19 June 2010 (UTC)

What is this obsession with strict literal accuracy of these terms? Does anyone do the same for anything else? Of course not. What horrors would ensue if we simply accept the new de facto convention as legitimate? (The de facto convention is that 12:00 a.m. denotes 12:00 midnight at the beginning of the day and 12:00 p.m. denotes noon.) Why doesn't anyone bring up the same point with anno Domini (AD)? "Strict logic" of the same sort used against the de facto convention for 12 a.m. and 12 p.m. shows that AD is not legitimate to use for any year. This is because we do not know in which year Christ was born (putting aside the contentious issue of the status of Christ -- regardless, the obvious intent of AD is with reference to the birth of Christ). So if a.m. and p.m. are illegitimate for 12:00, then AD is illegitimate for any year by the same type of literalist argument. PLEASE, literalists: explain why you object to 12:00 a.m. and p.m. but not to AD.

Why should we be stuck with the archaic and obselete definitions of ante and post mereidiem? These terms originated when people used Local Solar Time. In that system of time, noon really is when the sun crosses the meridian. But we now use a much more sophisticated system of Standard Time, time zones, and such. Only for a few select meridians is noon the time when the sun crosses the meridian. And these places oscillate throughout the year due to the equation of time!

More later. --Alan Feldman 2007/01/30 3:00 UTC

Noon itself has evolved over the years: Look in the dictionary -- it used to mean midnight!!! And etymologically speaking, it used to mean ninth hour.

I quote from the article in its current state:

The word "noon" is derived from Latin nona hora, the ninth hour of the day. As the Roman day started on 6.00 a.m., at sunrise, the first hour would have been from 6.00 till 7.00 a.m and the ninth hour from 2.00 till 3.00 p.m. These hours were important in monasteries, as different prayers were held on them.

The English word "noon" originally applied at 2.00 p.m., but by 1100 AD the meaning had shifted to "midday".

end of quote

So by 1100 AD the meaning of noon had shifted!!! Well, in the late 20th century, the meaning of a.m. and p.m. have shifted so that 12 a.m. is midnight at the beginning of the day and 12 p.m. is noon. At least this is the de facto meaning. Officials are behind the times; they are pretending that digital clocks don't exist.

So I ask: Why the different "etymological treatment" of noon, AD, and a.m./p.m.? Why can the first two terms evolve but not the third?

Alan E. Feldman 2007/02/06 02:07 UTC.

The reason being that 12am and 12pm are easily confused - I recently saw a document emanating from a university which referred to the same time of day as both 12am and 12pm. The fact is that - quite apart from the argument that words have meanings for a very good reason - noon and midnight are clear and unambiguous, which cannot be said for 12am and 12pm.

Stuart Robinson —Preceding unsigned comment added by (talk) 23:58, 6 July 2009 (UTC)

The article apparently contradicts itself by stating that it is not proper to refer to 12:00 as am or pm, but that it is considered good style (at least by the US government) to do so. I think the section stating that it is not proper should simply be removed. Such pedantry goes against the common usage of the terms and is possibly inaccurate. Times are usually stated to the minute, so 12:00 is actually accurate from midday to 12:01 pm. This justifies 12pm=noon.

The note that the official US style was opposite until 2000 amazes me. It may be that this confusion is a particularly American thing. In the UK, 12pm has been noon for as long as I can remember without anyone being confused about it, and in the large sections of the world which use the 24 hour clock there is even less confusion.

At any rate, this suggests that this confusion should not be given the prominence it has in the article. My suggested text is:

With 12-hour time notation there is some confusion as to whether noon should be written as 12:00 am or 12:00 pm. It is most common to refer to noon as 12 p.m and midnight as 12 a.m. and this is commonly displayed on digital clocks and computers. The 30th edition of the U.S. Government Style Manual (2008) recommends the use of "12 a.m." for midnight and "12 p.m." for noon (although the 29th edition recommended the opposite). To avoid the confusion, people often say "12 noon", as opposed to "12 midnight".

In 24-hour time notation, this confusion does not arise as noon is written as 12:00 while midnight is written as 00:00 (or, more unusually, 24:00).

Note that in my suggested texst I have removed the section on the ambiguity about midnight. It does not belong to an article about "noon" and should be transfered to the article for "midnight" - if it isn't already there.

BTW all of this reminded me of the classic conundrum: "At the stroke of midnight, is today the same as yesterday, or the same as tomorrow?" Agneau (talk) 22:32, 15 August 2009 (UTC)

confusion of p.m./a.m. noon and midnight

It becomes more confusing when one considers the military 24 hour clock, as at the 24th hour (midnight) one has a.m. when it is the last moment of the clock and day. Being the last moment of the 24 hour day, it should be p.m., not a.m. by rationality of the 24 hour clock/day. (talk) 02:30, 26 November 2009 (UTC)


"In addition, p.m. is often associated with night so 12 a.m. may seem to be midnight." What does this mean? Should the a.m. in that sentence actually be p.m.? --Banyan (talk) 18:31, 12 March 2008 (UTC)

Different etymology[edit]

I know a completely different etymology. According to this, noon is an incorrect rededuction from afternoon which again is derived from Old Norse "aftonon" (the evening).

High noon[edit]

I grew up knowing "high noon" as equivalent to "solar noon", rather than simply "noon", as would be implied by the unqualified link to this article from high noon, followed by this article's silence on the term. Tomertalk 06:49, 2 September 2009 (UTC)

Solar day - name?[edit]

Do you know what the name of the day in which the earliest sunset occurs (about 2 weeks before the solstice)? Any clues? Ol'Campy (talk) 21:10, 8 June 2011 (UTC)