Roshar Age?

[PiedPiper]

Is Roshar as old as Yolen? Because while humans migrated from Yolen to other planets -- meaning those new planets could theoretically have been new, or just created like Scadrial -- Roshar was actually home to the Singers, which could definitely have been around during the Shattering. So I'm curious as to how long it's been around. Is there a WoB for this?

[Nathrangking]

Roshar was created by uncle ado. 

[Dunkum]

Roshar definitely predates the shattering, as do some, but not all, of the Spren there.  Whether its as old as/older than Yolen I don't think we know.

[Karger]

We don't know the order in which Adonalsium created the planets.

[Elegy]

So, there's this WOB:

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Leiyan

I'm curious about the sun because it's described as white, and our sun is typically yellow. I assume it's a different type of star?

Brandon Sanderson

The yellowing of our sun is not actually caused...so our sun being yellow is not based on the star's actual color.

Leiyan

So is it bigger than our sun? Smaller? If there's anything you want to throw out there I'll take it.

Brandon Sanderson

Okay...I'm having to reach into my memory. This is not canon. Younger and larger, I believe it is both. Younger and larger.

Brandon Sanderson

The star's age, at Roshar...Earth astronomers would say that is a star which could not have planets with life on them.

Words of Radiance Philadelphia signing (March 21, 2014)

So yeah, while this is not canonical, it seems like the Rosharan System is one of the younger or youngest ones in the cosmere. (I noticed that the other systems with white stars - Taldain and Drominad - are both somewhat notable in terms of astronomy. I took that as Adonalsium experimenting with weirder solar system concepts before the Shattering.)

Since there is no fourth white star on the constellation map, Yolen's star is most probably either yellow or red, whatever that means. I like the thought that the red ones tend to be the oldest ones and it's one of those, but that's just guessing at this point.

[Gilphon]

So- Scadrial's definitely younger than Roshar. But it's likely that Roshar is younger than worlds that appear to be natural, like Yolen and Sel.