World Building Question: When is Noon?

This is a direct outgrowth of the previous World Building Question, and yes, continues the feature’s fascination with timekeeping that was only briefly interrupted by henotheism and monolatry. It’s a little harder to tie this back to world building, but I’ve got some of my standard questions at the end of this post. Next time I’ll find something else to talk about, I promise. That said, a simple question:

When is Noon?

To start answering this question, I’m going to take the computer programming route and define some terms first. This is important because people tend to think of “noon” and “12pm” as synonyms, but for the purpose of this post they are not. I will try my damnedest to be consistent.

Noon shall be defined as the time that the sun is at its zenith for the day in a given location. This is also called “solar noon,” but I’m going to simplify the term for this post.

12pm shall be defined as when a clock at a given location, set to that location’s time zone, reads 12pm.

Let’s continue now, shall we?

I brought up noon in my previous world building question that provided a brief history of the length of an hour, listed it as one of those clear delineating points of the day for a culture that uses the sun as its primary time telling device. Oh, that’s not to say it’s perfectly clear the exact moment that the sun is as high in the sky as it’s going to get, no big bright flash or bells going off, nothing like that. But it’s generally clear that, hey, the sun is pretty close to overhead.

Now, as to what time that was? Well, there was some disagreement on that. In modern cultures, with the 24 hour clock we’ve globally settled on, it’s close-ish to the middle of the day (more on that later). In several older cultures, this was true as well. Each new day started at sun-up and went until just before sun-up the following day. Of course, under this notion, noon would be about 6 hours into a 24 hour day. Some cultures considered the new day as starting at noon, so it would be 0 hours into the day. Some cultures counted a new day when the sun set, making noon about 18 hours into the day. These don’t make any actual difference, because things were getting done during the day, and all three ways of counting would agree on what day it is.

Today we count new days at midnight so noon happens 12 hours into the day at 12pm. Right?


For a time, yes. For a time when the sun was at its highest point of the day where you were it was 12pm, and twelve hours later would be midnight and the start of the new day. This held on for quite a while. Every city would have its own little mini time zone. In Boston it would be 8 minutes earlier than it was in New York, give or take. When it takes several days to get between cities, little differences of a few minutes in time don’t make a hell of a lot of difference. However when the railroad came around, that’s what things started to change. Which means we’re talking 19th century. Mid to late 19th century at that. What was called “railroad time” showed up in England around 1847 and in the United States in the 1880s. This evolved into the time zones we’re aware of today.

So what time is noon? Well, since an entire 1/24 slice of the globe is now on the same time, it can vary by an hour from one edge of a time zone to another. Except that time zones aren’t straight lines, they have bulges and juts that can create a wider gap than one hour. China, notably, has a single time zone that results in a four hour difference in when noon happens from the western extreme of the country to the eastern.

Then there’s Daylight Saving Time that throws everything off by another hour.

So to answer the question of when noon is. Today, March 21, 2013, noon in Washington DC will happen at 1:15pm. In Nashville, Tennessee and Amarillo, Texas, both in the same time zone, noon today will happen at 12:54pm and 1:54pm respectively. That’s a nearly two hour difference between 12pm and noon in west Texas. In Harbin, China, noon will come at 11:40am. In Kashgar, China, 3:03pm. The Kaliningrad Oblast, that little chunk of Russia that’s divorced from the main body of the country, uses the same time zone as St. Petersburg and Moscow. So while the city of Kaliningrad is almost due north of Warsaw, the former will hit noon at 1:45pm, the latter at 11:43am.

And so on.

Then there’s Zulu Time, aka UTC. Whatever you want to call it, the universal international time zone based around the non-DST adjusted time in Greenwich, UK (for various reasons that boil down to “because an Englishman figured out longitude at sea”) is where noon and 1200 hours are completely and forever divorced. Find the right place and noon will be at 0000 hours, or 12am. This is essential for organizations, like the US Navy, that need to coordinate on an international scale on vessels that might rapidly traverse time zones.

So when is noon? It depends on whether you’re on the western or eastern edge of your time zone. Whether you’re in a state or country currently observing Daylight Saving Time. Whether you’re in a culture that depends on rapid transit.  Whether you’re in a culture that needs/values uniformity of time for various transactions. Whether you’re observing a globally constant time. Noon as 12pm served humanity very well for an extremely long time. Now we’re moving increasingly into a society where the day is less defined as the sun and more defined as what we want it to be.

So what does that say about us as a global culture? What would it say about a global culture (either alien or future earth) that fully used UTC? What would it say of a culture that reached a similar technology as earth now has without any form of time zones or universal time, letting each city have its own slightly different time?

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  1. avatar

    #1 by Day Al-Mohamed on March 21, 2013 - 3:56 pm

    Ack. I found the discussion of noon interesting but the side note about longitude caught my attention.

    :) So…maybe navigtion next? Would love to hear about the history of the Prime Meridian. And how we could then extrapolate further to how to navigate amongst the stars…

    Ugh…now I’m tempted to go Google.

    • avatar

      #2 by DLThurston on March 21, 2013 - 4:59 pm

      As I recall, it’s actually directly related to noon. I’d have to double check this, but the trick is to make a clock capable of keeping accurate time at sea (which was the big problem) synching it with time at a known longitude, then seeing what the clock reads when the sun is at its apex. Little math and you’ve got your longitude.

    • avatar

      #3 by DLThurston on March 21, 2013 - 5:02 pm

      I have been thinking about doing navigation. Contrasting left, right, forward, and backwards with north, east, west, south. How maps are oriented. Eventually getting to longitude makes sense as part of that.

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