# A 24 hour day with less than 24 time zones

I'd like to have a world similar to earth in it's day cycle, meaning a 24 hour day measuring hours the way we currently do.

However, due to the planet's size, I'd like there to be less than 24 time zones (somewhere between 14 and 16).

I know in a Fantasy world you can technically do "anything" but I'd curious if it can actually be done (within reason).

From what I understand about time zones, we have 24 time zones because we have a 24 hour day and it basically means the sun's posiition at noon in one time zone will be the sun's position when it's noon in any other given time zone (in general, I know time zones are just made up lines on a map and it's not a perfect system). I'd like a similar setup on my world but with less time zones. Is that possible?

I also plan to have a fixed day/night cycle if that makes a difference (12 hours day / 12 hours night, no real shift throughout the year)

• You do realize we don't have 24 timezones. There are a few timezones that are X h and 30 m off of UTC. Jan 4 at 23:32
• time zones are completely arbitrary human invention, you could have two of them if you want.
– John
Jan 4 at 23:34
• The People's Republic covers 62 degrees of latitude, that is, more than four theoretical time zones. But the People's Republic uses exactly one time zone, namely that of Beijing, because democratic centralism is wonderful and people in Xinjiang don't mind that the time is not aligned with sun. (Or if they do mind, they keep it for themselves, or else.) Fun fact: when crossing the border between Tajikistan or Pakistan and the People's Republic, time changes by three hours. Jan 4 at 23:37
• Sorry, I think I asked the question slightly wrong, or I didn't emphasize what was important to me. I was talking about having the sun in the same place (relatively) at the same time in each zone. Which according to the answer below.. is doable if each zone is the same distance apart... which for a 16 zone planet, would be 1.5 hours apart). Jan 4 at 23:47
• This seems like one of those questions that is unwisely phrase to ask if something is possible (obviously 'yes') instead of asking whatever their real question might be. Can you have only 15 equally-spaced time zones? Sure, they will be 96 minutes apart. Between 1830 and 2010, railway stations and airports will have even more display clocks than they historically did so large numbers of travelers can tediously get the minutes right when changing their watches. Multi-zone clocks would be very popular so folks need not do the math in their head. Jan 5 at 1:13

Do they have a twenty-four-hour day?

If they use a different measurement, it's simple: just divvy them up according to their measurement.

If they do use a twenty-four-hour day, you need reasons why they divide it less finely. Usually this is for political reasons -- China is one time zone -- but coordination within a time zone is easier and may motivate it.

Notice that a 16-zone world has each zone a hour and a half later, but 14 would require them to be 1.714285 hours apart. This would be awkward.

Unless the zones are uneven -- sometime one hour, sometimes two, perhaps three or four, apart. That might be motivated by something like having fourteen landings on the planet, and as each settlement grew out, it kept the time of the landing.

• Okay, so I think I understand. If I have a 24 hour day with 16 zones, then each zone would need to be basically an hour and half apart (if the zones are equal). So if I do that, then the sun would be (relatively) in the same place at the same itme in each zone. Am I right? Jan 4 at 23:42
• Oh, yes. It would differ from one side to the other, of course, but consistently.
– Mary
Jan 4 at 23:43
• oh i just realized i typed that wrong. I meant the sun would be relatively in the same place at the same time in each zone, but I think you answered my question, which is Yes. Jan 4 at 23:45
• A smaller planet would seemingly desire more political/strategic time zone lines, rather than even and scientific ones. Lines we have now were consciously placed to avoid high population centers. That need would be even higher in a smaller planet. That they'd divide them evenly seems unlikely. They'd probably tend toward 2's and 3's when 1's were too small a change. Jan 5 at 0:25

How time zones are defined is just a matter of convention. Actually, we have way more than 24 zones: there are some with an offset of half or a quarter of an hour, and there's even a +14 zone so Kiribati can celebrate New Year earlier than any other country.

If the inhabitants of your world want to divide the world in 12 zones each 2 hours wide, or one zone for each continent, or any other scheme, that is entirely their prerogative (resp. yours)

• Oh I know and that makes sense. I guess I'm asking less about the zones themselves (since I know they are arbitrary), and more about making the zones work so that the sun's position is in (relatively) the same place at the same time in each zone. Does that make sense? Jan 4 at 23:36
• @Olandir: it depends on what the word "relatively" means. Here on Earth the theoretical ideal is that the civil time "ought to" be within ±30 minutes of the mean solar time; but in practice, China accepts −30 to +150 minutes offset from the mean solar time; France and Spain both use civil times which are +30 to +90 minutes offset from mean solar time; and so on. In your world, the conventional ideal may be ±60 minutes relative to mean solar time. Jan 4 at 23:47

Time zones were actually invented by a Canadian, Sir Sandford Fleming, in 1878, to solve the inherent problems of scheduling railroads without a standard time. Before standardized time and time zones, everyone declared 'high noon' locally, as the sun was exactly overhead of where they were. Time zones were based on the concept of 'high noon', but standardized within regions.

If one is not at all inclined to be constrained by the concept of 'high noon' being exactly 12:00 when the sun is directly overhead, then really one only needs one time zone for the entire planet. Otherwise you chose the number of time zones that closely achieve your objective of 'high noon', the sun being directly overhead, and the time being 12:00 to be within your parameters of acceptability. Is a sun that is 20 degrees offset from 'high noon' an acceptable alternative to '12:00'?

The closer to 'high noon' you want to get to, as the sun revolves around the earth, the more time zones you need. The reduction to absurdity, of course, reverts back to the original 'every town has its own time zone'. You set the allowable divergence to high noon, and you go from there. Sir Sandford Fleming arbitrarily broke time zones up by the hour, when in fact he could have done it by the half-hour, or fifteen minutes, or even every two hours. The objective and the result was a trade-off between ease of calculations, number of railroad 'localized schedules' necessary for a long cross-country trip, and conformity to 'high noon'. That depended a lot on the geographical width of the country. Britain, everything fit in one time zone. Canada, not so much. But ten schedules across the nation? Two? Five? The choice was arbitrary but easily calculated to be 'every hour'. Newfoundland, of course, was the exception.

A decade or so ago, time zones were pretty much dictated by television scheduling - "News at 11, half an hour earlier in Newfoundland'.

Prime time scheduling was the same time, everywhere. Almost.

Based on all the paremeters you have set, this can work only if everyone in your world lives on the equator, everyone lives on an island nation no larger than Austria, and each 16 island nation happens to be evenly spread apart along the equatorial axis.

I want to preface by saying that time is an abitrary construct created by humans. A "24-hour day" (or 12-hour day in some cultures) is an arbitrary number a day's length was divided by. The reason in many ancient systems we see "12" a lot is because before the innovation of decimals and fractions it is the most convient number to divide by 2, 3, 4, 6 and easy for people to break apart or share things, so its likely the reason why it is a number most intuitively and easily understood by many societies. A day's length could've easily be divided by 16 if you want matching the time zones, but you specifically want to retain a "24-hour day", presumably 24 hour clocks. So each time zone would not be scientifically decided, but geo-politically.

Here are the paremeters you have set:

1. 24-hour clocks.
2. 16 time zones.
3. The 12th hour of the day is when the sun reaches its apex.
4. Day/night cycle is exactly 12 hours each.

Let's start with #4. The only place where this is true is on the equatorial axis. If you want 16 time zones, then the adjudicators of each of the 16 time zones must reside along the equator. The rest of the world is uninhabited, which has varying plausibility depending on tech level. If it is an advanced civilization then perhaps a post global warming world where the ice caps melted.

Moving on to #3 - each nation adjudicating the time zone must be evenly spaced out such that the noon sun is at the apex. Each of these nation's size is necessarily restricted, because as a nation grow larger, the Eastern end and the Western borders will necessarily experience significant difference in the sun's position when the clock strikes 12:00. Within each of these 16 islands could be 16 independently unified or numerous divided nations, but there cannot be any significant habitation/travel beyond that, or the noon sun ceases to be at its apex. For this reason, the China model of merging time zone across large land mass would not work for you.

# Frame shift: Let's do 12 time zones on Earth.

I think by now most people are sick and tired of playing with their clocks for no obvious reason. Opinion is split between ending "daylights savings time" forever, or making it permanent. So why don't we do both? In the U.S., we set the clocks forward in the Central Zone and leave them alone in the Eastern Zone and all of a sudden we're on the way to having 12 time zones. If we align the boundaries with a long north-south set of state line boundaries, all the police reports and other such official documents would be using the same time, and if they were off because of zone issues, it would be by a more noticeable two-hour error. Imagine that...

If you actually need 14-16 zones with 24 hours, well, since it's a fantasy world you should use your Wand of Bend Math. Otherwise, we may actually have to do math. We need to change times when we cross by either 24/14, 24/15, or 24/16, which is 12/7, 8/5, or 3/2. Not sure if you're loving fractions, but the 3/2 is closes to convenient: all the time zones differ by 1 hour and 30 minutes, and there are 16 of them, which adds to 24 hours on your trip around the world.