Length of day on Arrakis


Moderators: Omphalos, Freakzilla, ᴶᵛᵀᴬ

User avatar
dunaddict
Posts: 211
Joined: 24 Sep 2008 09:09
Location: The Netherlands

Length of day on Arrakis

Post by dunaddict »

I am reading Dune again and I came across something that made me think. Leto in Arrakeen:
Leto stood in the foyer of his house, studying a note by the light of a single suspensor lamp. Dawn was yet a few hours away,
Later, near the Shield Wall, Jessica and Paul sleep during the day (presumably hours) to wait for nightfall.
He had awakened shortly before nightfall, sitting up in the sealed and darkened stilltent.
Sounds like the day and night are each several hours long. A normal day/night cycle.
Now, both Arrakeen and the Shield Wall are north of 60 degrees latitude. I guess somewhere between 65 and 70 degrees North.

On the Earth, at these high latitudes, the day is almost 24 hours long during the summer, and during winter the night is almost 24 hours long.
This happens because the Earth's axial tilt is 23 degrees and during summer everywhere within 23 degrees of the pole is permanently pointed at the Sun.

That means for Arrakis to have normal hours during day and night at high latitudes, the axial tilt must be close to zero . But close to zero axial tilt also means no seasons.

Yet, seasons are mentioned in the books. Some examples:
Frank Herbert in DUNE wrote:"Those are date palms," he said. "One date palm requires forty liters of water a day. A man requires but eight liters. A palm, then, equals five men. There are twenty palms out there--one hundred men." "But some of those people look at the trees hopefully." "They but hope some dates will fall, except it's the wrong season."
Frank Herbert in DUNE wrote:Dawn's gray line behind them was brightest at the notch in their horizon-calendar that marked the middle of autumn, the month of Caprock.
Frank Herbert in GEOD wrote:With First Moon almost directly overhead, it was quite light in the forest and, although these were the higher latitudes of Arrakis it was still warm from the heat of a summer day
So, has anybody read something about this, that could explain the discrepancy?
Last edited by dunaddict on 13 Jul 2009 11:13, edited 2 times in total.
User avatar
SandRider
Watermaster
Posts: 6163
Joined: 05 Oct 2008 16:14
Location: In the back of your mind. Always.
Contact:

Re: Length of day on Arrakis

Post by SandRider »

I imagine Chig & the some the brainiacs will chew this over
and come up with a lot of ideas and discussion.

my first gut reaction is that while Frank was a very smart
and insightful man, he was not a man of a particular science,
but a ponderer of ideas.

this is one of the "little details", perhaps even an "inconsistency",
that multiple re-readings & thoughtful attention will bring to light.

Frank gave alot of thought to the science in his work, but ultimately
he was more focused on story & ideas. Me, too. I'm not really a
"science fiction" fan, so alot of these types of discussions go right
on past me. It doesn't affect the beauty and importance of Frank's
DUNE.

(none of that applies to TheKeith, of course ...)

good catch, tho. I'm sure there are folks here who will enjoy
digging deeply into this issue ....
................ I exist only to amuse myself ................
ImageImage

I personally feel that this message board, Jacurutu, is full of hateful folks who don't know
how to fully interact with people.
~ "Spice Grandson" (Bryon Merrit) 08 June 2008
User avatar
Freakzilla
Lead Singer and Driver of the Winnebego
Posts: 18449
Joined: 05 Feb 2008 01:27
Location: Atlanta, Georgia, USA
Contact:

Re: Length of day on Arrakis

Post by Freakzilla »

Even a slight axial tilt would give some variation in seasons that plants would be sensitive to, would it not?

(Parts of the shield wall extend below the 60 degree line. Seitch Tabr and Cave of Birds are South of 60.)
Image
Paul of Dune was so bad it gave me a seizure that dislocated both of my shoulders and prolapsed my anus.
~Pink Snowman
User avatar
dunaddict
Posts: 211
Joined: 24 Sep 2008 09:09
Location: The Netherlands

Re: Length of day on Arrakis

Post by dunaddict »

Maybe. Dunno. But would a slight tilt be enough to use a horizon-calendar reliably?

(btw, I checked the map and Sietch Tabr is just below 60 degrees, but not much)
User avatar
Freakzilla
Lead Singer and Driver of the Winnebego
Posts: 18449
Joined: 05 Feb 2008 01:27
Location: Atlanta, Georgia, USA
Contact:

Re: Length of day on Arrakis

Post by Freakzilla »

dunaddict wrote:Maybe. Dunno. But would a slight tilt be enough to use a horizon-calendar reliably?

(btw, I checked the map and Sietch Tabr is just below 60 degrees, but not much)
They could have also brought their calander from another planet in the Zennsunni Migration. That would explain the reference to autumn but not the date palms.
Image
Paul of Dune was so bad it gave me a seizure that dislocated both of my shoulders and prolapsed my anus.
~Pink Snowman
User avatar
dunaddict
Posts: 211
Joined: 24 Sep 2008 09:09
Location: The Netherlands

Re: Length of day on Arrakis

Post by dunaddict »

I don't understand.... :?
The notches in the horizon calendar show you were the sun comes up in the different seasons. Using a horizon-calendar made on another planet makes no sense, because of the difference in axial tilt of the planet.
User avatar
A Thing of Eternity
Posts: 6090
Joined: 08 Apr 2008 15:35
Location: Calgary Alberta

Re: Length of day on Arrakis

Post by A Thing of Eternity »

I don't think there's enough text evidence to say that the day and night remain the same. Just because they don't do a full month of sun and a full month of night doesn't mean much, you could get pretty good seasons with much less tilt. Look at somewhere like lower Canada, nights and days change length, but not enough to make a big deal of it, and we go from -30 to +30 degrees.

So a planet with less tilt could certainly have seasons, though they would only be experienced fully farther north than they are here on earth.
Image
User avatar
SandChigger
KJASF Ground Zero
Posts: 14492
Joined: 08 Feb 2008 22:29
Location: A continuing state of irritation
Contact:

Re: Length of day on Arrakis

Post by SandChigger »

Actually, it's much more serious than that. Any tilt at all and you can't have regular day and night as depicted in the books.

I messed around with a lot of this kind of stuff over a year ago, back before shithead kicked me off DN. If he hasn't deleted the threads out of spite, they should still be there.

FH was terrible at math or didn't bother putting realistic details into the books. There's no definitive statement even on how big the planet is, although it's stated that the gravity is 0.9 Terran normal.

In one of the McDune books there's an epigraph about the planet having a (probably "artifical") axial tilt of zero. Byron confirmed that the "authors" said it was something found in FH's notes. I checked using Celestia and if there is any tilt at all, Arrakeen ends up in complete darkness for a few weeks (or months) during the winter. (Which translates into years in real terms, see below.)

Here are some calculated locations, based on the map at the front of Dune:

Arrakeen: 62 ° 17 ' 27 " N, 27 ° 47 ' 52 " W
Carthag: 65 ° 31 ' 55 " N, 15 ° 6 ' 17 " W

But ultimately that map is unreliable. Although it was drawn by a professional cartographer (of some fame, evidently), it wasn't based on accurate data. She probably just prettied up something FH had sketched by hand. So although we know that Arrakeen and Carthag are separated by 200 kilometers (from the text), we can't use that map to figure the radius of the planet (as you could with a properly executed one of that projection).

There's also a passage that tells the distance to the horizon when Leto is in the desert with Siona. But since we're not told as well the height of the dune they are standing on, you still can't get to the radius.

Maybe FH did it intentionally to keep people from figuring things out, or just to be a pain in the ass.

Either way, the Canopus system as portrayed in the books is implausible. As Denarius (sp? Mike Webb on Facebook; I think he's reposted some of his orbital calculations in the Dune group over there) showed over on DN as well, to have anything like tolerable temperatures with a star as large and hot as Canopus, Arrakis would have to be so far out that it would take many Standard Years just to make one orbit around the star. That would exacerbate the problems of seasons even more. ;)

I gave up worrying about it all and have been much happier since. :P
User avatar
A Thing of Eternity
Posts: 6090
Joined: 08 Apr 2008 15:35
Location: Calgary Alberta

Re: Length of day on Arrakis

Post by A Thing of Eternity »

I stand corrected. :oops:
Image
User avatar
SandChigger
KJASF Ground Zero
Posts: 14492
Joined: 08 Feb 2008 22:29
Location: A continuing state of irritation
Contact:

Re: Length of day on Arrakis

Post by SandChigger »

Sorry ... did I come on too strong again? :(

I'm running on fumes and heading for the futon any minute. More in the morn. :)
User avatar
A Thing of Eternity
Posts: 6090
Joined: 08 Apr 2008 15:35
Location: Calgary Alberta

Re: Length of day on Arrakis

Post by A Thing of Eternity »

SandChigger wrote:Sorry ... did I come on too strong again? :(
I'm running on fumes and heading for the futon any minute. More in the morn. :)
No, no. You were quite polite. I'm just embarrassed for trying to sound so authoritative based only on a hunch and some flawed logic and to then have been proven wrong.

I should know better!
Image
User avatar
GamePlayer
70mm God
Posts: 2993
Joined: 09 Feb 2008 11:26
Location: Toronto, Ontario, Canada

Re: Length of day on Arrakis

Post by GamePlayer »

Either way, this is good information to learn. An interesting exercise regardless of the outcome.
"They can chew you up, but they gotta spit you out."
User avatar
dunaddict
Posts: 211
Joined: 24 Sep 2008 09:09
Location: The Netherlands

Re: Length of day on Arrakis

Post by dunaddict »

SandChigger wrote: In one of the McDune books there's an epigraph about the planet having a (probably "artifical") axial tilt of zero. Byron confirmed that the "authors" said it was something found in FH's notes.
Do you remember which McDune it was? I would like to see that quote.
SandChigger wrote:I checked using Celestia and if there is any tilt at all, Arrakeen ends up in complete darkness for a few weeks (or months) during the winter.

Arrakeen: 62 ° 17 ' 27 " N, 27 ° 47 ' 52 " W
Carthag: 65 ° 31 ' 55 " N, 15 ° 6 ' 17 " W
Are you sure? The way I see it only the latitudes higher than (90 - axialtilt) would have polar nights. Look at this map:

Image

Suppose Arrakis only has a 1 degree tilt. Then everything south of 89N wouldn't see 24 hour nights.

I also used the formula on this site: http://www.exo.net/~pauld/activities/as ... ehenge.htm" onclick="window.open(this.href);return false;
to calculate how many degrees the sunrises are apart in summer and winter, if Arrakis only had a 1 degree tilt:

sin(max_degrees_from_due_east) = sin(axial_tilt) / cos(latitude).

With the latitude of Arrakeen (62 degrees), the formula says the sun would come up within 2.4 degrees north and south of due east in winter and summer.
So it IS possible to use a horizon calendar on a planet with such a small axial tilt. It just has to be measured very accurately.
User avatar
SandChigger
KJASF Ground Zero
Posts: 14492
Joined: 08 Feb 2008 22:29
Location: A continuing state of irritation
Contact:

Re: Length of day on Arrakis

Post by SandChigger »

dunaddict wrote:
SandChigger wrote: In one of the McDune books there's an epigraph about the planet having a (probably "artifical") axial tilt of zero. Byron confirmed that the "authors" said it was something found in FH's notes.
Do you remember which McDune it was? I would like to see that quote.
Yep. :) Actually, it's the first epigraph in House Corrino
The axis of spin for the planet Arrakis is at right angles to the radius of its orbit. The world itself is not a globe, but more a spinning top somewhat fat at the equator and concave toward the poles. There is a sense that this may be artificial, the product of some ancient artifice.
—Report of the Third Imperial Commission on Arrakis
I'd have to look through my email and DN PM records for the msg from Byron, and those are on another machine.

Notice anything strange about the epigraph? Doesn't the second sentence seem like an intrusion? A planet taking the form of an oblate spheroid is not unusual; it's true of our Earth, after all. And that fact makes the position of the following reference to "ancient artifice" seem really inane, whereas if you removed the middle sentence, "ancient artifice" could more naturally refer to the more unusual zero axial tilt. You have to wonder if KJA or BoBo inserted something to make it kewler, without really thinking (again).

Anyway, I don't have Celestial or my Duniverse extension on this machine either, but when I go looking for the msg from Byron I'll fire it up and take some screenshots. I unfortunately didn't record any of the parameters I was playing around with, but I'm fairly certain that it wasn't much of a tilt that put Arrakeen into a "night zone" for a good quarter of a year. I'll check to see what value I put in for the Arrakeen rotational period, too. ;)

This is one reason I was also playing around with rewriting the StarGen program to handle a star as massive as Canopus: to see if it would be possible to generate a solar system with an Earth-like planet in third position. Then I planned to just use its parameters and say shtoop to FH's bogus ones.

Poor ole guy just don't get no respect no more, does he? :|
"Let the dead give water to the dead. As for me, it's NO MORE FUCKING TEARS!"
User avatar
Hunchback Jack
Posts: 1983
Joined: 30 May 2008 15:02
Location: California, USA

Re: Length of day on Arrakis

Post by Hunchback Jack »

Even if the axial tilt is small, and the latitude is high, there will still be some times of year (i.e. spring and fall) where there will be "normal" days and nights. Could the above quote be during one of those times?

HBJ
User avatar
SandChigger
KJASF Ground Zero
Posts: 14492
Joined: 08 Feb 2008 22:29
Location: A continuing state of irritation
Contact:

Re: Length of day on Arrakis

Post by SandChigger »

It's possiboo? :)

I think the main point, from my PoV, is that there's no mention of non-normal day/night periods.

Here are the PMs from DN:
From: SandChigger
To: boardadmin
Posted: Sat Aug 12, 2006 9:03 pm
Subject: Arrakeen axial tilt

Hey, Byron, the next time you talk to Brian or Kevin, could you ask them about the inclusion of the information on the "axis of spin" at the beginning of House Corrino? Was it something they realized and worked in or was it in Frank's notes.

It seems like such a little thing, but it's absolutely essential for the environmental setting to behave as presented in Dune.
From: boardadmin
To: SandChigger
Posted: Wed Aug 16, 2006 5:46 am
Subject: Re: Arrakeen axial tilt

Here ya go! I spoke with Brian and Kevin yesterday and here is what they said...

"That came directly from Frank’s notes. He had a few pages where he drew up some basics about the planet, so we included the details in House Corrino."
_________________
The Almighty Moderator
A few pages of "basics about the planet", a few, or three and a half, or twenty-some pages of Outline, and billions and billions of pages of Notes! Right. :roll:
"Let the dead give water to the dead. As for me, it's NO MORE FUCKING TEARS!"
User avatar
dunaddict
Posts: 211
Joined: 24 Sep 2008 09:09
Location: The Netherlands

Re: Length of day on Arrakis

Post by dunaddict »

SandChigger wrote: "That came directly from Frank’s notes. He had a few pages where he drew up some basics about the planet, so we included the details in House Corrino."
That comment about the notes explains the out of place middle sentence. I suspect Frank Herbert notes might have read something like this:
Arrakis
  • The planet known as Dune; third planet of Canopus.
  • The axis of spin for the planet Arrakis is at right angles to the radius of its orbit. There is a sense that this may be artificial, the product of some ancient artifice.
  • In the wide belt contained by the 70-degree lines, north and south, temperatures for thousands of years haven't gone outside the 254-332 degrees (absolute) range, and this belt has long growing seasons where temperatures range, from 284 to 302 degrees absolute.
  • Similar to most planets, Arrakis is not a globe, but more a spinning top somewhat fat at the equator and concave toward the poles.
The first epigraph from House Corrino:
The axis of spin for the planet Arrakis is at right angles to the radius of its orbit. The world itself is not a globe, but more a spinning top somewhat fat at the equator and concave toward the poles. There is a sense that this may be artificial, the product of some ancient artifice.
—Report of the Third Imperial Commission on Arrakis
The mentally challenged duo must have randomly picked some parts they liked and concocted a "Science Nonsense" epigraph.
User avatar
inhuien
Posts: 3638
Joined: 09 Feb 2008 05:03

Re: Length of day on Arrakis

Post by inhuien »

There is a sense that this may be artificial, the product of some ancient artifice.
Notice that even when they attempt to sway one with writings from these spurious notes their subconscious mind tells the truth.
User avatar
Freakzilla
Lead Singer and Driver of the Winnebego
Posts: 18449
Joined: 05 Feb 2008 01:27
Location: Atlanta, Georgia, USA
Contact:

Re: Length of day on Arrakis

Post by Freakzilla »

Didn't Jessica think to herself about how low the sun was early on in Dune? I'll have to look latter...
Image
Paul of Dune was so bad it gave me a seizure that dislocated both of my shoulders and prolapsed my anus.
~Pink Snowman
User avatar
Freakzilla
Lead Singer and Driver of the Winnebego
Posts: 18449
Joined: 05 Feb 2008 01:27
Location: Atlanta, Georgia, USA
Contact:

Re: Length of day on Arrakis

Post by Freakzilla »

Freakzilla wrote:Didn't Jessica think to herself about how low the sun was early on in Dune? I'll have to look latter...
They heightened her feelings of confusion. She shuddered, glanced at the
slit windows high overhead. It was still early afternoon here, and in these
latitudes the sky looked black and cold -- so much darker than the warm blue of
Caladan. A pang of homesickness throbbed through her.

~Dune

:P
Image
Paul of Dune was so bad it gave me a seizure that dislocated both of my shoulders and prolapsed my anus.
~Pink Snowman
User avatar
dunaddict
Posts: 211
Joined: 24 Sep 2008 09:09
Location: The Netherlands

Re: Length of day on Arrakis

Post by dunaddict »

Strange. I don't understand what latitude has to do with how dark the sky appears...
And I found this quote in Dune that suggests the dark sky had to do with the lack of moisture:
She glanced out to the right at a slope humped with a wind-troubled graygreen of bushes--dusty leaves and dry claw branches. The too-dark sky hung over
the slope like a blot, and the milky light of the Arrakeen sun gave the scene a silver cast--light like the crysknife concealed in her bodice.
"The sky's so dark," she said.
"That's partly the lack of moisture," he said.
Does moisture in the air add to the brightness of the sky? I thought most of the light comes from scattered light from the air-molecules?
User avatar
Freakzilla
Lead Singer and Driver of the Winnebego
Posts: 18449
Joined: 05 Feb 2008 01:27
Location: Atlanta, Georgia, USA
Contact:

Re: Length of day on Arrakis

Post by Freakzilla »

dunaddict wrote:Strange. I don't understand what latitude has to do with how dark the sky appears...
And I found this quote in Dune that suggests the dark sky had to do with the lack of moisture:
She glanced out to the right at a slope humped with a wind-troubled graygreen of bushes--dusty leaves and dry claw branches. The too-dark sky hung over
the slope like a blot, and the milky light of the Arrakeen sun gave the scene a silver cast--light like the crysknife concealed in her bodice.
"The sky's so dark," she said.
"That's partly the lack of moisture," he said.
Does moisture in the air add to the brightness of the sky? I thought most of the light comes from scattered light from the air-molecules?
The color of the sky depends on the chemical composition of the atmosphere. The blue we see is because the molecules in the sky absorb red and yellow wavelengths (as well as the secondary and tirtiary colors between)and reflect the blue. That's actually the explaination for all the colors we see. The brightness would depend on how much light makes it through, I would think.

At northern lattitudes, the light would have to pass through more atmosphere because of the obtuse angle. That is why it is colder near the poles.
Image
Paul of Dune was so bad it gave me a seizure that dislocated both of my shoulders and prolapsed my anus.
~Pink Snowman
User avatar
dunaddict
Posts: 211
Joined: 24 Sep 2008 09:09
Location: The Netherlands

Re: Length of day on Arrakis

Post by dunaddict »

Yes, but does that make the sky significantly darker?

And can the "That's partly the lack of moisture" comment be correct?
User avatar
Freakzilla
Lead Singer and Driver of the Winnebego
Posts: 18449
Joined: 05 Feb 2008 01:27
Location: Atlanta, Georgia, USA
Contact:

Re: Length of day on Arrakis

Post by Freakzilla »

dunaddict wrote:Yes, but does that make the sky significantly darker?

And can the "That's partly the lack of moisture". comment be correct?
That I'm not sure about, intuitively it seems the opposite would be true. Fog is 99% humidity, IIRC.
Image
Paul of Dune was so bad it gave me a seizure that dislocated both of my shoulders and prolapsed my anus.
~Pink Snowman
User avatar
dunaddict
Posts: 211
Joined: 24 Sep 2008 09:09
Location: The Netherlands

Re: Length of day on Arrakis

Post by dunaddict »

There is also Mars. A desert planet with big dust-storms. Sound familiar?

Back in the seventies, before anything had landed on the surface, scientist thought the sky would be a dark-dark-blue, because of the thin atmosphere:
Image

When the Viking landers sent back the first pictures they were surprised the sky was a very bright red:
Image

Then they realized the storms blow enormous amounts of dust particles into the air. These dust particles scatter red light and make the sky a lot brighter than it would normally be.
Now, Dune, with the sandstorms, must have huge amounts of dust in the sky. So, there shouldn't be a dark sky. However, read this passage in Dune:
Paul glanced down at a conical projection chart of the northern Arrakeen latitudes spread on the table. "The desert belt and south polar regions are
marked uninhabitable. Is it the worms?"

"And the storms."
This means the northern latitudes don't suffer as much from storms as the rest of the planet: less dust in the air. This could explain the "and in these
latitudes the sky looked black
" quote.
Post Reply