Small worldbuilding issue - why do days have 27 hours?

[Lychnidos]

 

In the end the issue is that 27 isn't divisible by 2, i.e. the number of clear, natural, everybody-agrees-on parts of day, the homonymous day and the night.

 

Also, there isn't a size requirement for an orbiting object to be called a moon.

 

I've stayed out of this thread for a while because it was hurting my head, even though I was wondering the same thing.    While I'm no scientist or mathematician and someone may easily disprove what I'm about to say, I figured I'd share it anyhow.  We're thinking that Earth has 12 hours of day and 12 hours of night, but that's not what we actually have.  Throughout the year, at 41 degrees latitude (northern parts of the US), there's a maximum of 15 hours of daylight and a minimum of 9*.  At 65 degrees latitude (near Fairbanks, Alaska), there's a maximum of 21.1 hours of daylight and a minimum of 2.9 hours.

 

Perhaps the people of Eora were smart enough to consider how much daylight they have, on average, and used that for "day"?  I haven't actually looked at just how many hours long an Eora day or night cycle is, though, (a quick Wiki search turned up nothing) so I'll just throw out some numbers.  What if a day in Eora averages 15 hours long, while night averages 12 hours?

 

* Source:  Have fun!

 

 

I don't know who thinks that the daytime is always 12 hours(bar on the Equator), but take those minima and maxima, add them, divide by 2, what do you get?

 

Observe the curve on the site you linked, for every point that is above 12 hours there is a corresponding point below for the same distance, or just check the "show yearly average" box . You see the average length of daytime during a whole year for any place on Earth is 12 hours, also Equinoxes were all the jizz for any culture that noticed them.

Edited April 13, 2016 by Lychnidos

[Skirge01]

 

 

In the end the issue is that 27 isn't divisible by 2, i.e. the number of clear, natural, everybody-agrees-on parts of day, the homonymous day and the night.

 

Also, there isn't a size requirement for an orbiting object to be called a moon.

 

I've stayed out of this thread for a while because it was hurting my head, even though I was wondering the same thing.    While I'm no scientist or mathematician and someone may easily disprove what I'm about to say, I figured I'd share it anyhow.  We're thinking that Earth has 12 hours of day and 12 hours of night, but that's not what we actually have.  Throughout the year, at 41 degrees latitude (northern parts of the US), there's a maximum of 15 hours of daylight and a minimum of 9*.  At 65 degrees latitude (near Fairbanks, Alaska), there's a maximum of 21.1 hours of daylight and a minimum of 2.9 hours.

 

Perhaps the people of Eora were smart enough to consider how much daylight they have, on average, and used that for "day"?  I haven't actually looked at just how many hours long an Eora day or night cycle is, though, (a quick Wiki search turned up nothing) so I'll just throw out some numbers.  What if a day in Eora averages 15 hours long, while night averages 12 hours?

 

* Source:  Have fun!

 

 

I don't know who thinks that the daytime is always 12 hours(bar on the Equator), but take those minima and maxima, add them, divide by 2, what do you get?

 

Observe the curve on the site you linked, for every point that is above 12 hours there is a corresponding point below for the same distance, or just check the "show yearly average" box . You see the average length of daytime during a whole year for any place on Earth is 12 hours, also Equinoxes were all the jizz for any culture that noticed them.

 

 

Works great for Earth.  However, we're not dealing with Earth; rather, Eora.  In this instance, we're looking at an average of 27 hours per day, which is not divisible by 2, and that's the whole point of this thread (or so I thought):  Why are there 27 hours on Eora?  I offered a possible explanation for that.  As I attempted to explain, perhaps Eora's average is 27 hours, so they looked at how long the days and nights are, saw the difference in how much light there is versus darkness, and found there was NOT such a simple way to divide by two.  If the average daylight hours are 15 (or even more), you can't just go, "Hey, nighttime needs to start while it's still light out because we need a similar number of hours of 'night'."  My theory attempts to offer a bit of reasoning for the seemingly illogical number of hours in a day.

 

Also, you can't just add hours to a day since the hours are based on certain constants.  I recall a US Senator or Congressman trying to add an hour or two to the days and he was laughed at big-time.  Similarly, on Eora, 27 hours is based on certain constants which cannot be changed.  So, the mathematicians or scientists couldn't just say, "While it takes 27 hours for the planet to rotate, that number isn't divisible by 2, so let's just add an hour."

[JerekKruger]

 

Works great for Earth.  However, we're not dealing with Earth; rather, Eora.  In this instance, we're looking at an average of 27 hours per day, which is not divisible by 2, and that's the whole point of this thread (or so I thought):  Why are there 27 hours on Eora?  I offered a possible explanation for that.  As I attempted to explain, perhaps Eora's average is 27 hours, so they looked at how long the days and nights are, saw the difference in how much light there is versus darkness, and found there was NOT such a simple way to divide by two.  If the average daylight hours are 15 (or even more), you can't just go, "Hey, nighttime needs to start while it's still light out because we need a similar number of hours of 'night'."  My theory attempts to offer a bit of reasoning for the seemingly illogical number of hours in a day.

 

Also, you can't just add hours to a day since the hours are based on certain constants.  I recall a US Senator or Congressman trying to add an hour or two to the days and he was laughed at big-time.  Similarly, on Eora, 27 hours is based on certain constants which cannot be changed.  So, the mathematicians or scientists couldn't just say, "While it takes 27 hours for the planet to rotate, that number isn't divisible by 2, so let's just add an hour."

 

It'll work fine on Eora too. You'd need a pretty messed up orbit for it not to work, on any planet where life can reasonably survive you'll have an almost circular elliptical orbit and what Lychnidos describes will work just fine.

 

Your latter point isn't really right though. The hour was, originally, simply an arbitrary division of the day into smaller chunks, with 24 chosen for whatever reason (apparently the duodecimal system was in fairly common use across various parts of the ancient world so that's probably why). The key point here is the choice of division is arbitrary, they could have chosen to divide up the day into 22 parts, or 26 or even 329, but they chose 24.

 

Now rush forwards a few thousand years to the invention of the SI system of units where the second is chosen to be the unit of time. Since the length of a day is actually not a constant, defining a second to be 1/3600th of 1/24th of a day is not a good definition. Instead the second was redefined in terms of radioactive properties of caesium-133 as this is reliably constant. If we then define the hour to be 3600 second you'd be right that you can't add hours into the day, but this whole system is still based around a choice, namely the choice of caesium-133 and a number of oscillations of it. Change that choice and you change the number of seconds in the day and you can change the number of hours too. The reason we don't is because that choice has been carefully made to work with all the other SI units, and changing it would be a pain in the ass for scientists for very little benefit, but we could.

 

By the way, I think the story you mention about the US senators is actually referring to the Indiana Pi Bill, where the Indiana General Assembly attempted to define Pi to be 3.2 (well not directly, but as a consequence of their bill). Pi is slightly different to the definition of SI units in that it isn't based on an arbitrary choice. That means you can't change it.

[Lychnidos]

 

 

 

In the end the issue is that 27 isn't divisible by 2, i.e. the number of clear, natural, everybody-agrees-on parts of day, the homonymous day and the night.

 

Also, there isn't a size requirement for an orbiting object to be called a moon.

 

I've stayed out of this thread for a while because it was hurting my head, even though I was wondering the same thing.    While I'm no scientist or mathematician and someone may easily disprove what I'm about to say, I figured I'd share it anyhow.  We're thinking that Earth has 12 hours of day and 12 hours of night, but that's not what we actually have.  Throughout the year, at 41 degrees latitude (northern parts of the US), there's a maximum of 15 hours of daylight and a minimum of 9*.  At 65 degrees latitude (near Fairbanks, Alaska), there's a maximum of 21.1 hours of daylight and a minimum of 2.9 hours.

 

Perhaps the people of Eora were smart enough to consider how much daylight they have, on average, and used that for "day"?  I haven't actually looked at just how many hours long an Eora day or night cycle is, though, (a quick Wiki search turned up nothing) so I'll just throw out some numbers.  What if a day in Eora averages 15 hours long, while night averages 12 hours?

 

* Source:  Have fun!

 

 

I don't know who thinks that the daytime is always 12 hours(bar on the Equator), but take those minima and maxima, add them, divide by 2, what do you get?

 

Observe the curve on the site you linked, for every point that is above 12 hours there is a corresponding point below for the same distance, or just check the "show yearly average" box . You see the average length of daytime during a whole year for any place on Earth is 12 hours, also Equinoxes were all the jizz for any culture that noticed them.

 

 

Works great for Earth.  However, we're not dealing with Earth; rather, Eora.  In this instance, we're looking at an average of 27 hours per day, which is not divisible by 2, and that's the whole point of this thread (or so I thought):  Why are there 27 hours on Eora?  I offered a possible explanation for that.  As I attempted to explain, perhaps Eora's average is 27 hours, so they looked at how long the days and nights are, saw the difference in how much light there is versus darkness, and found there was NOT such a simple way to divide by two.  If the average daylight hours are 15 (or even more), you can't just go, "Hey, nighttime needs to start while it's still light out because we need a similar number of hours of 'night'."  My theory attempts to offer a bit of reasoning for the seemingly illogical number of hours in a day.

 

Also, you can't just add hours to a day since the hours are based on certain constants.  I recall a US Senator or Congressman trying to add an hour or two to the days and he was laughed at big-time.  Similarly, on Eora, 27 hours is based on certain constants which cannot be changed.  So, the mathematicians or scientists couldn't just say, "While it takes 27 hours for the planet to rotate, that number isn't divisible by 2, so let's just add an hour."

 

 

I used the numbers simply to illustrate a point, maybe I should have just said that the average length of day and night, respectively, anywhere on the planet during the course of a whole year, is half of the rotation period. For a planet to have different length daytime and nighttime it would need to have variable rotation speed during the course of a single rotation(i.e. day), and I don't know if that's possible. The number of hours a day is divided in as JerekKruger said doesn't have any physical backing, it's chosen for convenience, so why chose a number that isn't that convenient.

Edited April 14, 2016 by Lychnidos

[FlintlockJazz]

I always thought part of the reason they chose 27 hours was to enable players to have 8-hour rests without completely missing a time period in the day.  One thing that sometimes occurred to me while playing the IE games was that due to the way I played I often ended up sleeping around the same time each day, which sometimes caused me to barely see daylight for quite some time as I was always sleeping through it.  Probably not, but it does mean that player is more likely to rest and still wake up in the same day-period.

[JerekKruger]

That could be, though another solution would be to have us rest for 7 hours rather than 8.

[Fenixp]

I can deal with 27 hours long day, but mere 7 hours of rest? NEVER.

[JerekKruger]

I can deal with 27 hours long day, but mere 7 hours of rest? NEVER.

 

Well another alternative would be to base it off my student days and go with 11.

[vyvexthorne]

I feel the silliest thing in this 27 hour world is that your character still only sleeps 8 hours.

[Varana]

The number of hours in a day is, in itself, completely arbitrary. Whether we divide a day into 24 hours or 43 hours or 5 hours, is just a convention.

 

Also, historically, hours didn't need to be of equal length. It was fairly common to just divide the time between sunrise and sunset into 12 parts - which means that in summer, hours were longer than in winter. Measuring time during the night had additional difficulties, as the most accessible device for measuring time was a sundial. As human activity during nighttime was much lower than today, most people didn't need to know night hours anyway.

 

Irocco's calendar was the work of one man. It's entirely possible that he chose 27 hours for reasons like numerology ("3 is a perfect number, 9 is perfect squared, 3 times 9 even more so, and 81 is, well, impractical" or things like this).

We don't know whether there are astronomical reasons for the 27 hours. Cycles of the moon or important stars which give a neat number because they repeat every 3 days (see, 81!), or stuff like that.

Dividing the day into two parts (daytime and nighttime) is fine, but we could add twilight to this and get three phases - 10 hours of daytime, 10 hours of nighttime, 3.5 hours each of dawn and dusk, or things like that, depending on where Irocco lived and what he fancied.

[Elric Galad]

27 hours would have been perfect for Planescape setting and its rule of 3 )