How large is the Cosmere?

[+Oltux72]

Looking at the star map is instructive. Though we do not know whence it is seen from, except that it cannot be one of the systems marked on it, we can note that all the known systems' stars are easily visible. Now, except for Taldaine it looks like the worlds we have seen all orbit main sequence stars pretty similar to our sun. That means that they are really close to each other in astronomical terms. From our Earth the only true sun-like stars that seem bright to us in alpha-Centauri, which is less than 5 lightyears from us. Epsilon Eridani is about 10 lightyears. Tau Ceti isn't exactly a bright clearly visible star. Vega and Procyon are not similar to our sun.

Hence I would conclude that the Cosmere has a diameter of no more than twenty lightyears at most.

[Bejarden]

Brandon has said it is a small dwarf Galaxy I think 

[Kingsdaughter613]

1 hour ago, Oltux72 said:

Looking at the star map is instructive. Though we do not know whence it is seen from, except that it cannot be one of the systems marked on it, we can note that all the known systems' stars are easily visible. Now, except for Taldaine it looks like the worlds we have seen all orbit main sequence stars pretty similar to our sun. That means that they are really close to each other in astronomical terms. From our Earth the only true sun-like stars that seem bright to us in alpha-Centauri, which is less than 5 lightyears from us. Epsilon Eridani is about 10 lightyears. Tau Ceti isn't exactly a bright clearly visible star. Vega and Procyon are not similar to our sun.

Hence I would conclude that the Cosmere has a diameter of no more than twenty lightyears at most.

The Star map was created from an unknown point and is an artist’s depiction. It’s not necessarily accurate to how bright or dim the stars are when seen from that point. The only ones we know can be seen fairly consistently from most worlds are the three red stars.

[Fezzik]

1 hour ago, Bejardin1250 said:

Brandon has said it is a small dwarf Galaxy I think 

@Oltux72, Here is "about 50 light years across" from 2016,

https://wob.coppermind.net/events/59/#e725

Here is "a cluster instead of a dwarf galaxy" and "only dealing with 50 to 100 stars" from 2018,

https://wob.coppermind.net/events/324/#e9284

[+Oltux72]

3 hours ago, Kingsdaughter613 said:

The Star map was created from an unknown point and is an artist’s depiction. It’s not necessarily accurate to how bright or dim the stars are when seen from that point. The only ones we know can be seen fairly consistently from most worlds are the three red stars.

You need to be fairly close to see them at all. Sol would be barely visible to the human eye under the best possible conditions at 50 light years. Think an absolutely clear night in the Australian outback with no lights for hundreds of kilometers.

[Kingsdaughter613]

7 minutes ago, Oltux72 said:

You need to be fairly close to see them at all. Sol would be barely visible to the human eye under the best possible conditions at 50 light years. Think an absolutely clear night in the Australian outback with no lights for hundreds of kilometers.

Well, until fairly recently a lot of the Cosmere lacked modern tech. So less light and dust pollution to block the stars. And, for all we know, the artist was on a mountain top or using a telescope.

It’s also an artist’s depiction. We can’t see every star in a constellation all the time, but we can see them some of the time. An artist can make the stars as bright as they want as long as they know the stars are there. It’s unlikely all those constellations are visible at once either.

Indications are that the Cosmere is pretty small though, as it exists in a star cluster in a dwarf galaxy.

[RedBlue]

Only 50 to 100 stars?

My brain can’t decide between thinking ‘wow that’s tiny’ or ‘wow that’s huge’!

[Frustration]

2 hours ago, RedBlue said:

Only 50 to 100 stars?

My brain can’t decide between thinking ‘wow that’s tiny’ or ‘wow that’s huge’!

I can't comprehend how small that is.

[HSuperLee]

1 hour ago, Frustration said:

I can't comprehend how small that is.

Its about one-tenth the size of the smallest galaxy we know of, Segue 2.

[+Hoiditthroughthegrapevine]

The Coma Star Cluster in the constellation Coma Berenices is the second closest open cluster to earth (288 light years distant), and it has approximately 50 member stars. 

Depending on what angular size measurement you use (I've seen anywhere from 2° to 7.5°), the Coma Star cluster would have a radius anywhere from 10.1 lys to 37.8 lys. 

If the sun was at the center of an open cluster of the same radius as the Coma Star cluster, just listing stars of apparent magnitude 4.5 or greater (which would definitely appear on a star chart), then Alpha Centauri (1 confirmed and directly imaged planet), and Sirius would be encompassed by the smaller estimated radius. If the larger estimated radius were used that would add Epsilon Eridani (Ran), Procyon, tau Ceti (4 confirmed planets, 4 suspected planets), Omicron2 Eridani (1 known planet), Altair, eta Cassiopeiae (Achird), e Eridani (4 confirmed planets), delta Pavonis (The planet Caladan in Dune is the third planet orbiting delta Pavonis), beta Hydri (Southern Hemisphere constellation Hydrus), Vega, Fomalhaut (1 known planet), and pi3 Orionis (Tabit). 

Looking some of this stuff up I found this amazing gif on Wikipedia that shows a 3D rotation of the nearest stars to the sun (spoilered below). Get your 3d glasses if you have 'em because it looks super cool in 3D.

Spoiler

 

Edited March 16, 2021 by Hoiditthroughthegrapevine

[+Oltux72]

On 15.3.2021 at 0:48 AM, Frustration said:

I can't comprehend how small that is.

Yes, it is too small. There are about 70 stars visible on the chart alone. It seems to me that the whole cluster has to be in excess of a thousand stars for that to be likely.

The ratio of G stars to M stars is about 1 : 10. If this chart shows. How much of the sky does it show? Constellations that span more than a few percent of the sky don't make sense. (We have 88 constellations covering a sphere) Let's say it is 10% of the sky. M dwarf stars are really too dim to be seen (We cannot see Proxima Centauri and that is the closest. It is so dim that it was discovered in 1915 only)

4 hours ago, Hoiditthroughthegrapevine said:

 If the sun was at the center of an open cluster of the same radius as the Coma Star cluster, just listing stars of apparent magnitude 4.5 or greater (which would definitely appear on a star chart), then Alpha Centauri (1 confirmed and directly imaged planet), and Sirius would be encompassed by the smaller estimated radius. If the larger estimated radius were used that would add Epsilon Eridani (Ran), Procyon, tau Ceti (4 confirmed planets, 4 suspected planets), Omicron2 Eridani (1 known planet), Altair, eta Cassiopeiae (Achird), e Eridani (4 confirmed planets), delta Pavonis (The planet Caladan in Dune is the third planet orbiting delta Pavonis), beta Hydri (Southern Hemisphere constellation Hydrus), Vega, Fomalhaut (1 known planet), and pi3 Orionis (Tabit). 

A star of apparent magnitude 4.5 would appear on a proper star chart, but that is not what we see with the inhabitated planets. They do not merely appear. They make up the backbones of constellations. And if you look at Centaurus, to stay with the example, only two of the bright suns forming the constellation can be called sun-like at the most charitable interpretation.

4 hours ago, Hoiditthroughthegrapevine said:

Looking some of this stuff up I found this amazing gif on Wikipedia that shows a 3D rotation of the nearest stars to the sun (spoilered below). Get your 3d glasses if you have 'em because it looks super cool in 3D.

Impressive

4 hours ago, Hoiditthroughthegrapevine said:

  Hide contents

 

And how many of those you listed are remotely similar to the Sun? Counting F, G and K stars: Alpha Centauri, Tau Ceti, Epsilon Eridiani, Procyon, Omicron2 Eridani, Eta Cassiopeiae, e Eridani, Delta Pavonis, Beta Hydri and pi3 Orionis. If we subtract the subgiants that is two less. And three of these stars are not exactly all that bright. 10 at the nicest interpretation.

Yet for the Cosmere we have 6 such stars in a subsection of the sky. So something is unusual.

[Weltall]

34 minutes ago, Oltux72 said:

Yes, it is too small. There are about 70 stars visible on the chart alone. It seems to me that the whole cluster has to be in excess of a thousand stars for that to be likely.

Word of Isaac is that not all of the stars seen in the chart are actually part of the Cosmere. What we're seeing with at least some of those is stars in the larger galaxy that aren't part of the star cluster we know as the Cosmere.

Quote

Yet for the Cosmere we have 6 such stars in a subsection of the sky. So something is unusual.

'An Adonalsium Did It.'

Edited March 16, 2021 by Weltall

[+Hoiditthroughthegrapevine]

1 hour ago, Oltux72 said:

And how many of those you listed are remotely similar to the Sun? Counting F, G and K stars: Alpha Centauri, Tau Ceti, Epsilon Eridiani, Procyon, Omicron2 Eridani, Eta Cassiopeiae, e Eridani, Delta Pavonis, Beta Hydri and pi3 Orionis. If we subtract the subgiants that is two less. And three of these stars are not exactly all that bright. 10 at the nicest interpretation.

Yet for the Cosmere we have 6 such stars in a subsection of the sky. So something is unusual.

Well, I think your classical assumption that only F, G, and K class Main Sequence stars are candidates for intelligent life isn't necessarily warranted in a stellar system with a known all powerful creator. You no longer necessarily need a star with a stellar lifespan in the billions of years, because the planet doesn't need to be given enough time to independently evolve life when life can be directly created or seeded upon it. 

Also the very strange Taldain binary star system underscores this point, Taldain is tidally locked between a white dwarf (facing Darkside) and a class AIa, or AIab or AIb blue-white supergiant (facing Dayside). So the Dayside facing star could be very similar to the star Deneb in the constellation Cygnus (which is an A2Ia supergiant). 

A lot of the conditions we restrict our search to for extraterrestrial life from here on Earth don't apply in a Star System where stellar objects can be directly manipulated by near omniscient entities to fine tune the habitable qualities of the planets in a given solar system (like Rashek and Sazed did in the Scadrial system). 

Red hypergiants are most likely off the table because the habitable zone is wholly encompassed within their volume. But with the inbaked instability of the orbits of the Rosharan moons and the fact that the continent of Roshar needs to be magically sustained or else it will erode into the sea heavily implies that extreme permanence was not a high priority design goal for Adonalsium. Even stars of spectral class O are possible candidates though they have a stellar lifespan of around 10 million years and the habitable zone is roughly some 500 au distant. It would be pretty sweet if the shard of [redacted RoW spoiler, but if you've read it you know which one I mean, wink, wink] invested in and populated with life a small asteroid or planetoid caught in the gravitational pull of one of the rarest types of Stars. And with the amount of mass being shed by that giant star there would be an inordinate amount of stellar wind to possibly fly interstellar kites with. 

One other kind of interesting point is that if the Cosmere is an Open Star Cluster, it's much less likely to be a closed system, other stellar bodies could drift through its non rigidly encompassed border, or it could itself cross into or through another such cluster. What are the ramifications for that? How does Investiture not leak from the system. Interesting to speculate on for sure. 

Edited March 16, 2021 by Hoiditthroughthegrapevine
Typos, always typos

[+Oltux72]

2 hours ago, Hoiditthroughthegrapevine said:

Well, I think your classical assumption that only F, G, and K class Main Sequence stars are candidates for intelligent life isn't necessarily warranted in a stellar system with a known all powerful creator. You no longer necessarily need a star with a stellar lifespan in the billions of years, because the planet doesn't need to be given enough time to independently evolve life when life can be directly created or seeded upon it. 

But I do not need to make assumptions. The suns of the settled worlds of the Cosmere, safe for Taldaine, just are not blue monster stars or dim red dwarfs.

2 hours ago, Hoiditthroughthegrapevine said:

Red hypergiants are most likely off the table because the habitable zone is wholly encompassed within their volume. But with the inbaked instability of the orbits of the Rosharan moons and the fact that the continent of Roshar needs to be magically sustained or else it will erode into the sea heavily implies that extreme permanence was not a high priority design goal for Adonalsium. Even stars of spectral class O are possible candidates though they have a stellar lifespan of around 10 million years and the habitable zone is roughly some 500 au distant. It would be pretty sweet if the shard of [redacted RoW spoiler, but if you've read it you know which one I mean, wink, wink] invested in and populated with life a small asteroid or planetoid caught in the gravitational pull of one of the rarest types of Stars. And with the amount of mass being shed by that giant star there would be an inordinate amount of stellar wind to possibly fly interstellar kites with. 

It would be cool, but again we have not seen such worlds and the length of the years alone would make them extremely obvious.

2 hours ago, Hoiditthroughthegrapevine said:

One other kind of interesting point is that if the Cosmere is an Open Star Cluster, it's much less likely to be a closed system, other stellar bodies could drift through its non rigidly encompassed border, or it could itself cross into or through another such cluster. What are the ramifications for that? How does Investiture not leak from the system. Interesting to speculate on for sure. 

Provided it is old enough.