Setting limits on the size of Roshar (the planet) and Roshar (the continent)

[Aleksiel]

I upvoted you just so I could neutralize the downvote you had been given. But comments like these are both unhelpful and unneeded. Especially on a site such as this. The forums should be a safe place to all where they can obsess however much they like over Brandon's works. I know you probably didn't mean to be as harsh as it seems but please ask yourself next time, "Is what I'm posting adding anything to the discussion ?" and act accordingly. Thank you.

 

Thank you, I realize now that my comment was inappropriate. I edited it  to express my opinion better, apologize for the misunderstanding (I was aiming for something entirely different as a meaning than what I suppose most people made of my comment, but that's really on me) and hopefully contribute to the topic.

[Aether]

Thank you, I realize now that my comment was inappropriate. I edited it  to express my opinion better, apologize for the misunderstanding (I was aiming for something entirely different as a meaning than what I suppose most people made of my comment, but that's really on me) and hopefully contribute to the topic.

Change approved of. Up-vote to to counter-act all the down-votes.

[QuantumHarmonix]

The prospect of uncovering hidden clues is what makes this type of speculation fun for me. But it does remind me of that Rumsfeld quote about Known Unknowns, and Unknown Unknowns.  Because it's a fictional world there are going to be a multitude of factors that are just going to be missing. BS and company might know them but felt they were too minor to mention, or they might not have ever crossed their minds. But even those minor missing factors have the potential to make the results so riddled with errors that they really don't do us any good. What I would find really amusing is if Brandon slips one of the missing variables found by these types of calculations into one of the other books. It might not do us any good, but it would be kind of an easter egg for us. 

[WeiryWriter]

You should see my equirectangular and azimuthal equidistant map projections. Except you won't, not anytime soon.

 

I see Peter post things like this and go "AHHHH! Peter is such a horrible tease."  And then I think about what I would do in his position and realized I would be soooo much worse...

[Natans]

I see Peter post things like this and go "AHHHH! Peter is such a horrible tease."  And then I think about what I would do in his position and realized I would be soooo much worse...

 

What worse that don't know? Know that information exist but the person that know are messing up your head =)

 

This kind of thing aren't of Honor

 

When Harmony put Scandrial in the proper place in the solar system he, correctly, put the planet in a position that the sun wouldn't be to far(cold) of to close(hot).

 

So i kind believe that within in the power of a Shard to make a planet take precise 500 days to give a full round around the sun =)

[PeterAhlstrom]

Could you tell me what's wrong with the radius calculation? I went over the calculation again, and I couldn't find anything wrong with it. 

Yeah, sorry, I looked more closely at what you wrote and maybe you didn't miss anything after all.

 

I think it's safe to say that with an orbital distance between that of the Earth and Mars, assuming a planetary density somewhere between Earth's and Mars's is a fairly good bet. Except that I'm not at all certain Roshar's sun has the same mass as our sun—in fact it very likely does not for various reasons. And I haven't spent enough time looking into how that will affect things.

[Everstorm]

Yeah, sorry, I looked more closely at what you wrote and maybe you didn't miss anything after all.

 

I think it's safe to say that with an orbital distance between that of the Earth and Mars, assuming a planetary density somewhere between Earth's and Mars's is a fairly good bet. Except that I'm not at all certain Roshar's sun has the same mass as our sun—in fact it very likely does not for various reasons. And I haven't spent enough time looking into how that will affect things.

I think the Sun's mass comes into play only when we talk about the length of the year. If the planet is further away than Earth though, it  means that Roshar's sun has to be brighter than Earth's sun. This cartoon of the goldilocks zone for various solar intensities shows why. 

http://en.wikipedia.org/wiki/Circumstellar_habitable_zone

 

Either this or the composition of the atmosphere is probably slightly different and contains more greenhouse gases which can retain heat better. 

 

I think as far as fan speculation goes, it is probably not rewarding to go into the size of the sun because the intensity could depend on so many factors like what the mass of the star is, what stage in its lifetime it is at, etc., and we clearly have insufficient information to deal with that right now.

 

The fact that Roshar's density is less than that of Earth does imply though that it is perhaps bigger than we had expected, and there could be as yet unexplored regions on the other side of the globe which could be relevant. This maybe throws a wrench in the "Origin of highstorms = Place of honor => Urithru is on the west coast" theory, so this piece of information doesn't make me too happy. But thanks for the tidbits, Peter!

[PeterAhlstrom]

The length of the year is one thing we were talking about.

You have more information than you have realized you have.

[Shardlet]

One thing I haven't seen considered yet is that Roshar's single land mass occupies an unknown portion of the southern hemisphere.  The entire northern hemisphere is substantially oceanic as well as a significant portion of the southern.  The depth of the oceans are also unknown.  Since the water will have a density vastly lower than the land masses, this would have a profound effect on your average density of the planet and therefore on your radius calculations.  Also consider that plate tectonics are not a factor on Roshar.  This suggests to me that the outer crust of Roshar is significantly thicker than the crust on Earth.  The solid crust would have a higher density than the magma beneath it, of course.

[Everstorm]

One thing I haven't seen considered yet is that Roshar's single land mass occupies an unknown portion of the southern hemisphere.  The entire northern hemisphere is substantially oceanic as well as a significant portion of the southern.  The depth of the oceans are also unknown.  Since the water will have a density vastly lower than the land masses, this would have a profound effect on your average density of the planet and therefore on your radius calculations.  Also consider that plate tectonics are not a factor on Roshar.  This suggests to me that the outer crust of Roshar is significantly thicker than the crust on Earth.  The solid crust would have a higher density than the magma beneath it, of course.

I may be wrong on this, but I don't think the ocean/land cover will affect the mass of the planet all that much. The dense solid mantle and the core probably contribute much more significantly to it. This link  has some back of the envelope calculations about the same.

 

The length of the year is one thing we were talking about.

You have more information than you have realized you have.

Well, what I meant was that there are too many variables right now. If we had the radius or the density, we could use those to estimate the mass of the planet. If we had the distance from the sun (along with the length of the year), we could find out the mass of the sun. 

 

If there is more information, it is really well hidden, because I've read this book six times already, though not with the intention of making distance calculations (yet) . I will probably read it once more in the run up to the WoR release, and keep my eyes peeled for size-of-things clues.

 

P.S. I hope you're not trolling, but it's okay even if you are since I was going to read the book again anyway

 

EDIT: Okay, we can actually make some inferences. In Earth time, the length of their year is 400 days. Mars' year is 687 days. So if their sun was the exact same mass as our Sun, we could say for sure how far away Roshar was from it's sun. T^2 is proportional to R^3 (Kepler's laws). We know at least that their sun is in the same ballpark range as our sun, otherwise for a planet placed between Earth and Mars, the time period would be much shorter. 

Edited February 3, 2014 by Darkeye

[Shardlet]

I may be wrong on this, but I don't think the ocean/land cover will affect the mass of the planet all that much. The dense solid mantle and the core probably contribute much more significantly to it. This link  has some back of the envelope calculations about the same.

 

It really depends on the relative thickness of the crust and the depth of the oceans.  Consider of course that the density of sea water is 1.028 g/cm3.  That is almost 20 percent of the average density that was relied upon.  So a significantly higher percentage of water could have a very significant effect on the average density.  We can make assumptions for the crust thickness (based on assumptions for overcoming tectonics and still maintaining a magnetic field).  But, ocean depth seems to me to be much more nebulous.  We could base it off of the Earth's average ocean depth, but that is a shot in the dark unless we have some valid reason to suspect a corresponding average depth on Roshar. 

[PeterAhlstrom]

If there is more information, it is really well hidden, because I've read this book six times already, though not with the intention of making distance calculations (yet) . I will probably read it once more in the run up to the WoR release, and keep my eyes peeled for size-of-things clues.

 

P.S. I hope you're not trolling, but it's okay even if you are since I was going to read the book again anyway

There's still at least one piece of relevant information in the book that I haven't seen mentioned.

[Awesomeness Summoned]

There's still at least one piece of relevant information in the book that I haven't seen mentioned.

Well then go ahead. You can be the first to mention it 

[Moogle]

There's still at least one piece of relevant information in the book that I haven't seen mentioned.

 

Perhaps something to do with the moons? Hmm. You've got me curious all of a sudden. I think I'll go reread TWoK this weekend in its entirety.

[PeterAhlstrom]

Not the moons, though that is another interesting topic.

[Shardbearer]

Hmm. Kaladin's stormriding?

[Robot Aztec]

Is It who fast hgihstorms go when kal rides one and we see places a long way away and we know it takes one nightso maybe that is it?

[Natans]

About the moons they have some kind of affect in tidal variation and/or season ? I ask because the planet have a very anomaly season variation and epic highstorms (that probably are more related with the cognitive aspects of the planet or something but even so).

 

If the planet are smaller than earth and have more moons that (we don't know the size of the moons) this woundn't influence the tidal and season variation ?

 

Another question. In the wit history he said something about the time that taked to the ship find land after they left the main continent ? 

Edited February 4, 2014 by Natans

[Everstorm]

The child of Honor chapter has nothing obvious in it. If it does, it is well hidden. That was one of the first ones I checked. My guess is that it is either Shallan or Navani talking about their respective journeys.

EDIT: I looked at all the maps on the Stormlight wiki, and I think the Shattered Plains maps could be useful. The distance from the various camps to the Tower may have been mentioned or estimated in the book and that could provide a scale for the entire map. I don't have my kindle on me right now, so I can't check to make sure. I'll try to look at it tonight. 

Edited February 4, 2014 by Darkeye

[Relaz]

Start looking at the maps, and comparing them. The one of Alethkar before the prologue is especially interesting.

[Cromptj]

There aren't any volcanoes shown on the map or mentioned to my knowledge. Therefore, Roshar may well not have a molten and/or iron core and could be the same size or larger than the earth because of its lower density. The lack of a molten core also suggests that either the core was once molten but now the planet is tectonically dead and that the gemstones outside the great shells are naturally occurring or that all gemstones on Roshar are not created through geological processes.

Edited February 5, 2014 by Cromptj

[TomR]

There aren't any volcanoes shown on the map or mentioned to my knowledge. Therefore, Roshar may well not have a molten and/or iron core and could be the same size or larger than the earth because of its lower density. 

 

The lack of volcanos is presumably due to no tectonics meaning no subduction.  However, I wouldn't count on Roshar not having an iron core since it presumably has a magnetic field (given that its sun hasn't blown away its atmosphere a la Mars).  Jovian worlds are thought to get their magnetic fields from ice or hydrogen, but all terrestrial sized planets are believed to get theirs from their spinning molten iron cores.  Of course, this is also a fantasy world; the Shards could be playing a role, and Roshar may not need a magnetic field at all.  However, the map of the continent has a north and south marked, so I still think it's likely they have one.

Edited February 5, 2014 by TomR

[Cromptj]

I thought that south and north were just relative to the highstorms.

[TomR]

I thought that south and north were just relative to the highstorms.

I'm not aware of any mentions of magnetic north yet, so maybe that's all they are.  That's why I tried to cover my butt by saying the Shards could be playing a role  I enjoy geeking out with the astrophysics or whatever and trying to figure out how things may work, but I don't forget that normal science just may not apply.  Atmospheric Pressure and Division (depending on what it does) may make the Lorentz force redundant.

[Cromptj]

About the magnetic field, I thought that one of Roshar's moons might be a gas giant which shelters it against solar wind and radiation. I have no evidence, but it is possible.