Popular Post Leiyan Posted March 1, 2014 Popular Post Report Share Posted March 1, 2014 (edited) EDIT: There's been a lot of discussion and revision to my original ideas, and I would recommend basically skipping this first post for the most part. It is, however, important to read the first two sections ("Observations" & "Related Information") as they set up some of the information given in the books and by Peter which is used to support the rest of the findings. Here are links to my most recent analysis: The orbits of the moons precess as the planet orbits the sun: http://www.17thshard.com/forum/topic/6334-the-moons-of-roshar/?p=103069 (I've since dropped the notion that they share exactly the same orbit, better language would be to say the moons share the same period and have very similar orbits....more on this in the posts below.) The orbit of the moons is in the opposite direction compared to Roshar's rotation: http://www.17thshard.com/forum/topic/6334-the-moons-of-roshar/?p=103135 (more details in the next link...) More about the orbits being in the opposite direction & how the orbits must be inclined when compared to the plane of the Roshar's orbit around its sun: http://www.17thshard.com/forum/topic/6334-the-moons-of-roshar/?p=103175 Preliminary calculations for the orbits: http://www.17thshard.com/forum/topic/6334-the-moons-of-roshar/?p=103350 There is, of course, a lot of good discussion and contributions between all these posts that I would recommend! I'm in the processes of re-organizing all of the information that has been deduced into a single document, so it can be read without the need to jump between posts and it would skip past the incorrect hypotheses. ----Orignal Opening Post (read the first two sections, the rest is now discarded)---- All this talk about the moons of Roshar in the other two threads got me thinking… Based on the "observations" provided in the book and the comments from Peter, I’ve come up with some speculations about the moons of Roshar. First…the data! Observations: “The sun set in the west, but the wagons kept rolling. Violet Salas peeked over the horizon to the east, seeming hesitant at first, as if making sure the sun had vanished.” WoK Chpt 2 “Nomon—the middle moon—had begun to rise, bathing the city in pale blue light. Staying up this late had been a rare privilege for her in her father’s house…” WoK Chpt 8 “Szeth looked over his shoulder, wishing that the Second Sister—known as Nomon to these Easterners—had risen to give a little more light.” WoK I-3 “Salas’s violet light shone in the sky outside, but the small moon wasn’t bright enough to illuminate the barn’s interior, and the creature had moved into a shadowed recess.” WoK Chpt 19 “Nomon—the middle moon—shone with his pale, blue-white light.” WoK Chpt 23 “Nomon was setting in the west, and the small green disk of Mishim—the final moon—was rising in the east.” WoK Chpt 23 “Two hours later, at Salas’s first violet light, Rock and Kaladin walked back into the lumberyard. It was just past sunset, and many of the bridgemen would soon be going to sleep.” WoK Chpt 27 “Kaladin smiled, leaning back, looking upward toward the dark sky and the large sapphire moon.” WoK Chpt 73 Related Information: PeterAhlstrom, on 06 Feb 2014 - 2:06 PM, said: Each moon is in the sky only once per day and moves across the sky in a couple to a few hours. What does that tell us about their orbits? http://www.17thshard.com/forum/topic/5854-setting-limits-on-the-size-of-roshar-the-planet-and-roshar-the-continent/?p=94890 PeterAhlstrom, on 06 Feb 2014 - 5:15 PM, said: I expect the moons were put in their current orbits artificially, but by whom or what I do not know. On astronomical terms, these are not stable orbits, but astronomical terms means millions of years. A few thousand or even a few hundred thousand years are no problem. http://www.17thshard.com/forum/topic/5854-setting-limits-on-the-size-of-roshar-the-planet-and-roshar-the-continent/?p=94976 PeterAhlstrom, on 27 Feb 2014 - 11:37 PM, said: They are very small. Think Phobos and you'll be in the ballpark. http://www.17thshard.com/forum/topic/6249-will-we-see-interplanetarlunar-travel-in-future-books/?p=102426 ------ Here are the “facts” based on the observations: Salas and Mishim are both described as “small” moons. (WoK Chpt 19 & 23) Nomon is described as a “large” moon. (WoK Chpt 73) Salas always rises first, Nomon always rises second, and Mishim always rises third. [szeth refers to Nomon as the Second Sister (WoK 1-3), Nomon is refered to as the “middle moon” (WoK Chpt 8 & 23), and Mishim is called the “final moon” (WoK Chpt 23), by process of elimination Salas is first.] Orbital Locations of the Moons: Since the moons always rise in the same order (Salas, Nomon, Mishim), all three moons have to be the same distance away from Roshar. They all have to be in the same orbit. Otherwise they would appear in a different order on various nights over time. And this means… the moons are at Lagrangian points! The Lagrangian points are stable locations where objects can share the same orbit. Jupiter, for example, shares its orbit with asteroids at Lagrangian points 4 and 5. Using the above image to describe the Sun-Jupiter system, the Sun is at the center, Jupiter is the purple body to the right (between L1 and L2) and the Jupiter Trojan asteroids are found around L4 and L5. Lagrangian points 4 and 5 are always about 60 degrees from the body on the right (Jupiter, in this example). In the case of these moons, Roshar would be the central body, while the most massive moon (based on the size, this would presumably be Nomon) would take the purple point near L1L2 (where Jupiter was), and the other two would have to sit at the other Lagrangian points. There is one final piece of information that helps us lock down the locations of the moons: from WoK Chpt 23 it’s clearly states that Nomon is setting just as Mishim is rising, i.e. they are 180 degrees apart…on opposite sides of their orbit. For the Roshar-Nomon system I propose that Salas is at Lagrangian point 4 and Mishim is at Lagrangian point 3. In regards to the orbits of the moons not being perfect circles… Jupiter has an orbital eccentricity of about 0.049. The Earth’s eccentricity is only 0.016. Even Mars, with an eccentricity of 0.093(!!), still has trojan asteroids at its Lagrangian points. I think it’s safe to say the Roshar-Nomon system has Lagrangian points. It is, however, notable that L3 is typically a very specific point and it can be unstable…I’m hoping the “artificial placement” of these moons helps to explain how Mishim ended up in such a perfect placement. Size Approximations: Since Peter suggested Phobos was a ballpark, I’m going to go ahead and copy it as a template for the moons of Roshar. First, Phobos orbits at approximately 9000 km from Mars, so I’m going to put the Three Sisters at that distance from Roshar. Because Nomon seems to reflect enough light to see by at night (WoK Chpt 8), which our Moon does as well, and I don’t have anything better to go on, I’m going to assume that Nomon looks to be visibly the same size as our Moon. Our Moon is about .5 degrees in diameter on the night sky. An object at 9000 km away would have to be 80 km in diameter to appear as .5 degrees in diameter on the night sky. As for the small moons, I’ll look to Phobos as an example again. Phobos is 22 km in diameter. From the surface of Mars, Phobos would appear to be about .14 degrees big on the night sky. In other words, a moon the size and distance of Phobos would appear to be a little under the diameter of the Moon as seen it from Earth. Assuming that the small moons, Salas and Mishim, have relatively the same diameter and mass, and that Nomon is significantly larger, these numbers seem decently reasonable to me. It would make the two “small” moons appear to be about 1/3 the size of the “large” moon, and the “large” moon would appear similar in size to our Moon. Closing Thoughts & Questions: It’s after midnight, so I don’t want to try and figure this out now, but I think we can get some more solid information on the orbital period of the moons based on what is presented in the Observations and Information sections. Peter said the moons were in the sky “only once per day,” which is interesting.... Especially considering that all observations of the moons only seem to take place at night (anyone have any daytime references?) There are two comparisons between sunset and Salas moonrise that I can recall; WoK Chpts 2 and 27. In both chapters, Kaladin observes Salas rising just after the sun had set. I don’t recall any mention of Salas and Nomon being in the sky together, but if my Lagrangian point theory holds I would keep an eye out for it in the upcoming books. It is, however, clear that Noman is setting when Mishim is rising (WoK Chpt 23). If the moons are only in the sky at night (as visible from Alethkar at least), does Salas always rise just after sunset? I’d love some lunar observations from Shinovar to see if the moons are visible during the day over on that side of the world! It is also possible that the two small moons are simply too small to reflect enough light, and the large moon, being blue, might just blend in with the sky. Still it seems really really weird to me that we only have nighttime lunar observations. Something to consider! I can’t wait to read of additional lunar observations in Words of Radiance!!!!!! ((edited for ugly formatting error I didn't notice in the previews)) Edited March 3, 2014 by Leiyan 30 Link to comment Share on other sites More sharing options...
bartbug Posted March 1, 2014 Report Share Posted March 1, 2014 This is awesome. Just one piece of info to add to your brilliant coalition of information: I'm pretty sure that Peter said that they do not have perfect orbits (can't remember exact terminology, but sometimes they are really close to Roshar, and other times really far. An eliptical orbit, I think). But anyways, this is cool. I think I'm going to ask Brandon about this at the signing. Link to comment Share on other sites More sharing options...
PeterAhlstrom Posted March 1, 2014 Report Share Posted March 1, 2014 There are some flaws in this analysis that should become apparent. 10 Link to comment Share on other sites More sharing options...
Leiyan Posted March 1, 2014 Author Report Share Posted March 1, 2014 (edited) This is awesome. Just one piece of info to add to your brilliant coalition of information: I'm pretty sure that Peter said that they do not have perfect orbits (can't remember exact terminology, but sometimes they are really close to Roshar, and other times really far. An eliptical orbit, I think). But anyways, this is cool. I think I'm going to ask Brandon about this at the signing.I covered elliptical orbits, but I didn't out right say that. Eccentricity is a measure of how elliptical an orbit is. I pointed out that even Mars, with its highly eccentric orbit has asteroids at its Lagrange an points. However, I'm not brushed up enough on orbits and eccentricity to test how elliptical an orbit can get...more thoughts for later.Please let me know what you ask and what response you get!! I'm also attending a signing and have some questions in mind, would hate to repeat you! There are some flaws in this analysis that should become apparent.Well, it's my first shot at this sort of thing. =) I hope you mean the flaws will become apparent in WoR? Edited March 1, 2014 by Leiyan Link to comment Share on other sites More sharing options...
bartbug Posted March 1, 2014 Report Share Posted March 1, 2014 Heh, I know nothing, other than the speculation I've seen in the other threads that touch on this. Roshar's moons are much much closer than our moon. Their elliptical orbits bring them closer to Roshar's surface during the night than geosynchronous altitude. -Peter This should impact things significantly, I think. It was in a fairly recent thread. Great job, Leiyan, he who knows more about moons than I do. 1 Link to comment Share on other sites More sharing options...
Leiyan Posted March 1, 2014 Author Report Share Posted March 1, 2014 (edited) Oh I didn't catch that one! Hmm! OK I also admit I did read a post saying they were closer than synchronous atltitude, like Phobos, and I kinda skipped past factoring that for now...but I didn't catch just how eccentric the orbits were described by Peter. I can't wait to try and figure all this out. =D. Edit: But in the morning when I can think better. >.> Edited March 1, 2014 by Leiyan Link to comment Share on other sites More sharing options...
Eri Posted March 1, 2014 Report Share Posted March 1, 2014 (edited) I agree with the Lagrangian points and Nomon being the second body. About the orbit size: it can be calculated from Roshar's mass and moons' orbiting time. Yes, I believe the moons always rise and set at the same hour. Also they rise at east and set at west, like the sun. Which means they are synchronised with the sun's position on the sky. This sets their orbiting time to the same as Roshar's orbiting of the sun. (Indeed, and not to one day! I'll post some gifs to explain, but I'm kinda busy.) Which is rather long, but actually unknown (as I've mentioned in another thread, I don't see why time between Weepings would have to be the time it takes the planet to orbit the sun). This implies a big orbit radius. If the moons are on sky at daytime, just invisible, they could have much shorter period and therefore orbit radius. PS: Can anyone give source link about the high eccentricity? Edited March 1, 2014 by Eri 1 Link to comment Share on other sites More sharing options...
Swimmingly Posted March 1, 2014 Report Share Posted March 1, 2014 I though peter mentioned that they come closer than geosynchronous orbit? Link to comment Share on other sites More sharing options...
bartbug Posted March 1, 2014 Report Share Posted March 1, 2014 Yeah, he did. Link to comment Share on other sites More sharing options...
Eri Posted March 1, 2014 Report Share Posted March 1, 2014 (edited) Any link? Edit: Thank you. Also, I'm not suggesting geostationery orbit; tis wouldn't actually make sense. Though if they come closer than geostationary… wow, this must be a really spiky ellipse. If they are "much closer" in general and really are on the sky one time per day, and go from east to west then I must be missing something, because I don't see how it would make sense. But I suppose they do get much further and the long axis is what I thought the radius will be. BTW does anyone know how hich eccentricity (of moon's orbit, not planet's) affect Lagrangian points? I couldn't find in on Google. Edited March 1, 2014 by Eri Link to comment Share on other sites More sharing options...
Swimmingly Posted March 1, 2014 Report Share Posted March 1, 2014 (edited) http://www.17thshard.com/forum/topic/6249-will-we-see-interplanetarlunar-travel-in-future-books/page-2 Roshar's moons are much much closer than our moon. Their elliptical orbits bring them closer to Roshar's surface during the night than geosynchronous altitude. Edited March 1, 2014 by Swimmingly 1 Link to comment Share on other sites More sharing options...
king of nowhere Posted March 1, 2014 Report Share Posted March 1, 2014 yeah, we know the orbital period is one rosharan day (20 hours for us), and roshar gravity is 0.7 g, so we should be able to calculate geosyncronous orbit. I'm too lazy, and too rusty on that, to do it myself. I also don't know how eccentricity fits into it Link to comment Share on other sites More sharing options...
Eri Posted March 1, 2014 Report Share Posted March 1, 2014 yeah, we know the orbital period is one rosharan day (20 hours for us), This is not true. Take the planet's rotation into account. I really don't have time to do the gifs, but a period of 1 day = something "hangs" in the same point of the sky (think: Calamity in Steelheart), not it appears always at the same hour. Link to comment Share on other sites More sharing options...
Humph Posted March 1, 2014 Report Share Posted March 1, 2014 Leiyan, upvote for all the research. Very informative. However, It is not at all clear that all three moons share the same orbital plane. Can anyone shed light on whether Lagrange points can exist in a highly elliptical orbit with three orbiting bodies in the same orbital, i.e. one in which the distance of the orbiting mass to focus constantly varies, and would vary significantly at each moment amongst the three moons (which may or may not have differing masses)? Each moon moving across the sky in only a few hours implies a high orbiting velocity for the time in which they are visible in the night sky, or a quick rotational velocity of Roshar, or both. I don't know how a Rosharian day compares to an earth day, nor do I know Roshar's diameter; but high orbiting velocity seems to fit well with a highly eccentric orbit with Roshar at one focus, as the moon slingshots past Roshar. Link to comment Share on other sites More sharing options...
Humph Posted March 1, 2014 Report Share Posted March 1, 2014 Take the planet's rotation into account. I really don't have time to do the gifs, but a period of 1 day = something "hangs" in the same point of the sky (think: Calamity in Steelheart), not it appears always at the same hour. Do we know for a fact that the direction of Roshar's rotation is the same direction of orbit for the moons? I was under the impression that they are in different directions, one clockwise, the other counterclockwise. Link to comment Share on other sites More sharing options...
DocHoliday Posted March 1, 2014 Report Share Posted March 1, 2014 An elliptical orbit bringing a Phobos sized moon out of geosynchronous orbit would appear larger than the .14° Leiyan is proposing wouldn't it? His Szeth quote also mentions that Nomon only gives a little more light than Salas, not necessarily alot more light. Being that Salas produces violet light I think it's fair to say that it does a poor job of actually illuminating nighttime Roshar. Yet Kaladin and Rock are able to see well enough by it to make their way through camp by it. But if Nomon, a blue white moon, only produces slightly more light, then it probably isn't much larger (to appearances) than Salas. All this is to say that I don't think they're necessarily in the same orbit around Roshar. Since we are aware that they appear in the same order every night for thousands of years, I think its more than nature taking it's course. That seems artificial. 1 Link to comment Share on other sites More sharing options...
Mysty Posted March 1, 2014 Report Share Posted March 1, 2014 @Leiyan, you said "I don’t recall any mention of Salas and Nomon being in the sky together, but if my Lagrangian point theory holds I would keep an eye out for it in the upcoming books." However, you missed one quote about the moons in Szeth's interlude "a work off art" "It was the time between the first two moons, the darkest period of the night. The hateful hour, his people called it..." Otherwise, I like your analysis, it makes sense to a non-astronomer. 1 Link to comment Share on other sites More sharing options...
Leiyan Posted March 1, 2014 Author Report Share Posted March 1, 2014 @Leiyan, you said "I don’t recall any mention of Salas and Nomon being in the sky together, but if my Lagrangian point theory holds I would keep an eye out for it in the upcoming books." However, you missed one quote about the moons in Szeth's interlude "a work off art" "It was the time between the first two moons, the darkest period of the night. The hateful hour, his people called it..." Otherwise, I like your analysis, it makes sense to a non-astronomer. Oh, great catch, thank you! I'm putting all these quotes into an excel spreadsheet... hopefully, I'll get time to turn this into a database... I have some more ideas I am currently working out. =D Link to comment Share on other sites More sharing options...
Leiyan Posted March 1, 2014 Author Report Share Posted March 1, 2014 Okay, I still believe these moons must share the same orbit, in order to always appear in the same order, and at the same time night to night. They wouldn't call them "First" "Second" and "Third" Sister if they weren't always in order, and, as Mysty pointed out, they wouldn't have a name for the time between Salas and Nomon ("It was the time between the first two moons, the darkest period of the night. The hateful hour, his people called it...", I-6) if it wasn't consistent. Though, I still need to math out how/where the moons could exist in a shared orbit before I can back this up fully. Roshar's moons are much much closer than our moon. Their elliptical orbits bring them closer to Roshar's surface during the night than geosynchronous altitude. -Peter I totally missed this before....the elliptical orbits bring them closer to Roshar's surface during the night... always during the night. So the elliptical orbit of the moons must precess such that the apogee (furthest point from Roshar) is always pointing towards the sun, and the perigee (closest point to Roshar) is always pointing away from the sun. Here's a badly drawn image to illustrate... It's the (out of scale) location of Roshar, and the orbit of Roshar's moons, as Roshar orbits relative to the sun. 3 Link to comment Share on other sites More sharing options...
Eri Posted March 1, 2014 Report Share Posted March 1, 2014 I don't know how a Rosharian day compares to an earth day, nor do I know Roshar's diameter; but high orbiting velocity seems to fit well with a highly eccentric orbit with Roshar at one focus, as the moon slingshots past Roshar. Roshar day = 1/500 R year = 1.1 Earth year / 500 = about 0.78 Earth day = a little below 19 Earth hours Do we know for a fact that the direction of Roshar's rotation is the same direction of orbit for the moons? I was under the impression that they are in different directions, one clockwise, the other counterclockwise. Erm... I'm not sure if I understand your question, but we know that moons' and sun's perceived movement is in the same direction (they rise at east and set at west). At least sun and 2 of the moons I'm sure of. Direction of moons' orbit is a hard one... according to my hypothesis (synced with Roshar orbiting its star) we can't know it, because it depends on Roshar's orbiting, not its rotation. I think. However I'm not really good at astronomy, most of my "research" about Roshar astronomy = I've asked my husband (who studied physics) and I've read Wikipedia. 1 Link to comment Share on other sites More sharing options...
masaru Posted March 1, 2014 Report Share Posted March 1, 2014 I love reading analysis from someone who clearly has a science background. It takes something I just passed over without a thought in the text and makes it much more interesting. All of this suggests to me that the moons are actually artificial. Roshar has a very... strange... relationship with technology that is hard to relate to, but it seems quite within the realm of possibility that the moons were made and placed into orbit, maybe for observation, maybe as bases. Link to comment Share on other sites More sharing options...
Leiyan Posted March 1, 2014 Author Report Share Posted March 1, 2014 Do we know for a fact that the direction of Roshar's rotation is the same direction of orbit for the moons? I was under the impression that they are in different directions, one clockwise, the other counterclockwise. I believe you are correct. Roshar spins CCW and the lunar orbit travels CW (or vice versa). If Salas rises in the sky opposite the sunset as seen from Alethkar, and then remains in the sky during the night, it cannot be moving the same direction as Roshars rotation at high orbital speed, or it would just disappear below the eastern horizon and stay ahead of the visible nighttime sky as seen from Alethkar. 2 Link to comment Share on other sites More sharing options...
Leiyan Posted March 2, 2014 Author Report Share Posted March 2, 2014 I have more ideas I want to share about the moons, basically a complete revision of my opening post… please keep in mind, this is all preliminary, based on limited observations, and I expect revisions and we get more info… First, since it is already known that Roshar does not have an axes title (http://lunarubato.tumblr.com/post/42954839930/ok-so-here-is-the-information-we-collected-from), we know that their day and night cycles would be equal in length everywhere on the planet. I’m just going to use 10hr days and 10hr nights as arbitrary numbers, since it doesn’t really matter what I use as long as they are equal lengths. Salas rises at sunset (WoK Chpt 2 & 27). Salas sets before Nomon rises, this is the “darkest period of the night” (I-6), and it lasts about one Rosharn hour (called “the hateful hour” I-6). Mishim rises in the east when Nomon is setting in the west (Chpt 23). Because the times between moonrises are described so precisely, I still believe they have to be in the same orbit. So they have the same orbital period. However, the orbit is elliptical, which means the moons will travel faster around perigee and then slower as they reach apogee. “Roshar's moons are much much closer than our moon. Their elliptical orbits bring them closer to Roshar's surface during the night than geosynchronous altitude.” -Peter As I said in a previous post, I’m beginning to think the lunar orbit precesses so that apogee is always towards the sun, and perigee is always away from the sun. This means that if Salas is opposite the sun when rising, Salas is basically at perigee, and is at the full moon state. Also, in order for any of the above observations to make any sense, I think the moons have to be travelling in the opposite direction as Roshar is rotating, and the moons orbit has to average out to geosynchronous, i.e. the moons need to go around Roshar exactly once per day. “Each moon is in the sky only once per day and moves across the sky in a couple to a few hours. What does that tell us about their orbits?” -Peter Typically, when you think of a geosynchronous orbit, when when object orbits once per day, you think of an object that “hangs” in the sky (like Calamity from Steelheart). It’s always at the same place relative to the ground, no matter what time of day it is. But this is only when the satellite is orbiting in the same direction as the planets rotation. If it’s moving at an overall geosynchronous orbit, but in the opposite direction of the planets rotation, then you’ll see it move…and you’ll see it move fast. Here’s another poorly drawn image! This is a view of the orbit of Roshar and its moons as seen from above looking down. The little stick figure, for the sake of this exercise, is standing on the equator at sunset. If you were standing where the figure is in the image, you would see the sun in the western horizon. As Roshar rotates counterclockwise the figure would be moving around the night side of the planet, and then at the top of the image of Roshar they would experience sunrise. Speculation on the orbits of Salas, Nomon, and Mishim: Because Salas is rising at about the same time the sun is setting, Salas must be opposite the sun, and it must be near to perigee in its full moon phase. As Salas moves clockwise, and Roshar orbits counterclockwise, Salas would immediately begin waning. It would be seen to set in the west in only a matter of hours, I’m guessing an hour before midnight and probably be seen as a half moon. Salas starts bright-ish, but competing with the setting sun, and only gets dimmer as it moves across the sky. Then we have to wait a bit of time, as between Salas and Nomon is “the darkest period of the night” known as “the hateful hour.” Nomon would rise around midnight as a waxing gibbous moon. Since it is midnight (and midnight in Alethkar means you’re facing directly at perigee) Nomon is moving towards the fastest part of its orbit. It will scoot along the sky rather quickly phasing into full moon, and then slow down a bit as it passes perigee and phases out of full moon. It would set, I’m guessing maybe 2 or 3 hours after rising, as a waning gibbous, or near half-moon. While Nomon is near the western horizon, Mishim rises in the east. Mishim would rise perhaps as a waxing half-moon. It will move faster as it goes across the sky, and I’m thinking it would set about 2 or 3 hours after it rises. This would mean it sets as it is near perigee and full moon phase, and about the same time as sunrise. I also think the plane of the moons orbit is inclined compared to the plane of Roshar’s orbit around the sun. If the lunar orbit was in the same plane, or near the same plane, as Roshar’s, you would get a lunar eclipse of some kind every single night. Since there is no mention of anything like this at all, I think it’s safe to say the plane of lunar orbit must be tilted significantly. Also, because Alethkar (and the whole super continent) is in the southern hemisphere (the “Frostlands” are southeast of Alethkar and the “tropical” Reshi Islands are to the north), I think the inclination of the lunar orbits is to the south at perigee and to the north at apogee. In the (badly drawn and out of scale) image below, the sun is in the center, and Roshar is visualized at two opposite locations in its orbit, and the orbit would be going into and out of the page. The moons orbits would pass above the sun as seen from Roshar when they are towards the day side. From the southern hemisphere’s perspective, if the moons were visible during the day, they would be low on the horizon. When the moons orbit takes them to the night side of the southern hemisphere, they would be able to cross higher in the sky. This is all leading me to other ideas, but those I would want to math out first... 11 Link to comment Share on other sites More sharing options...
DocHoliday Posted March 2, 2014 Report Share Posted March 2, 2014 Hmm. I'm still of the opinion that the moons are not in the same orbit. The timing of the moon rise is very specific. But as I previously stated, I don't think this is due to your Langrous point speculation, and owes more to intentional placement of these astral objects. I have no evidence beyond initial observations of the amount of light provided however. Also of we take the Rosharan day of 19 hours, we get 9+1/2 hours of darkness. If Salas is in the air for 3 hours, we have 1 hour of no moonlight. That leaves us with approximately 2+3/4 hours of light for Nomon and Mishim. Would that help your math Leiyan? 1 Link to comment Share on other sites More sharing options...
Eri Posted March 2, 2014 Report Share Posted March 2, 2014 (edited) Wow, huge work you put into that!Also, thx for the info about zero tilt, I suspected it, but didn't see a WoB on it before. I’m beginning to think the lunar orbit precesses so that apogee is always towards the sun, and perigee is always away from the sun. This means that if Salas is opposite the sun when rising, Salas is basically at perigee, and is at the full moon state. I agree that it's a logical conclusion from observation.But this is a very strange phenomenon, normally impossible.It might be caused by:- Planet's gravity… if the speed of light was much lower (relativity magics, I don't quite get it, but my husband said it's possoble and Sun works on Mercury like that IRL, but for a planet to affect its moon in such way c wold need to be lower) – unlikely for Cosmere to have different c, I think.- Star's gravity, with very high excentricity (like 30?) of moon's orbit it's possible. This would however make it all unstable and you can forget about any Lagrangian points… but hey, we have a future-seeing beings and gravity-affecting magics. Instability? What instability? ^^- Generally by magic, we've seen it messing with gravity already. Some big gravityspren (hmm… it reminds me of Cusi-whatever's the name) / Jezren / Cultivation / something similarly powerful. And seeing the future or really good at maths, so probably Cultivation. Also, the question here is: why and what for would somebody do it? and the moons orbit has to average out to geosynchronous, i.e. the moons need to go around Roshar exactly once per day. I think you forget to take Roshar's rotation into account.1/day orbit, in different orientation (I'm not sure if we can call it geosync) would mean they are visible 1 times per day (one in day and one in night) and it would be impossible for almost all night to have moonlight. Which it doesa, I believe, since the darkest time is a gap between moons, and there is no mention of another darkest hour. Edit: I have no visual imagination. What you wrote makes a full lot of sense, I think it must be right. (though still I'm not sure about calling it geosync if it's in different direction, but I agree with general idea)With an orbit like that they already move very quick by night (in terms of angular speed). From the southern hemisphere’s perspective, if the moons were visible during the day, they would be low on the horizon. When the moons orbit takes them to the night side of the southern hemisphere, they would be able to cross higher in the sky. As far as I could figure this out (by direction of sunlight, but I'm not 100% sure), Roshar continent is on southern hemisphere. I wonder why do they call it "south" then – but this is another matter… Edited March 3, 2014 by Eri Link to comment Share on other sites More sharing options...
Recommended Posts