What type of star does Athas orbit, scientifically speaking?

More specifically, does the pattern of magical tampering with Athas’ Sun follow any known star life cycle observed by modern science, and if so, what type of star is it?

By extension, what is the eventual fate of the star, barring more magical tampering, and how much time is left?

Also curious if there are any Dark Sun Spelljammer references (looking for details of other celestial bodies in the Athas solar system)…

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You know, I’ve often wondered about that, too. I’d guess a type O star. There is a particular type/mass that can legitimately cycle between a “blue giant”, “yellow hypergiant”, “red supergiant”, and back again. Probably a type of Wolf-Rayet star (?) for most of its life, which means it belches out tons of mutating radiation and clouds in an unstable fashion, if memory serves. It would fit with the pattern set up in the lore, and retain the notion that the star can be dialed back to what it was in a previous age. The stars are short-lived, so life on Athas would need an explanation outside of evolution, but the cycles between colors/sizes do happen on the scale of thousands to tens of thousands of years. Would be great for a game in which a DM wanted to completely lessen the importance of the Pristine Tower, as the star could be held responsible for mutating radiation and its own color/size shifts… maybe even The Grey.

Second to that, I read an article a few months back on “zombie stars” that can go supernova multiple times, but still survive. On principle alone, that screams “Dark Sun” to me.

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Nothing official as far as i know, but there is this: http://www.spelljammer.org/worlds/CrimsonSphere/

I started thinking about this (and the spelljammer stuff DM’s Revenge posted) a while back when I start my current campaign.
I went in with the assumption that Athas’ sun was a Sol-type star with Athas at some distance beyond the midpoint of the star’s habitable zone. I think what happened was that Rajaat drained enough energy or what have you from the star to push it forward on it’s life cycle close to the Red Giant phase. The star would turn redder, start to swell, and the habitable zone would move outward.
Just my own unverifiable personal gnosis on the subject.

Yeah, but the blue stage needs to be accounted for.

I think it’s pretty obvious the changes in Athas’ star were meant to evoke the life cycle of a typical main sequence star (at least as it was understood in the late 80s / early 90s).

Of course that’s not going to make any sense if you think too hard about it.

I always justified it as a main sequence star being forced between its various stages unnaturally, and went with the idea that as the star itself changed states and its goldilocks zone changed in orbital size/distance, the effects of the Pristine’s Tower’s leeching included altering the orbit of Athas to maintain a (relatively speaking) optimal orbital distance.

I’ve also considered that Athas is actually a moon orbiting Ral, and Guthay is either a smaller satellite orbiting Atlas, or a sister-moon orbiting Ral as well.

Ultimately, again, rule of cool. Take inspiration from real world phenomena and science, but don’t get caught trying to find exact real-world explanations that will 100% fit.

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In reference to Dark Sun and Spelljammer, I remember reading a specific section in one of the official Sourcebooks which covered how the Phlogiston allows access to the various AD&D Settings. It goes like this:
1). All Systems are enclosed in an impenetrable Crystal Sphere or Shell, which keeps the Phlogiston out. Spelljamming allows one in and out.
2). The Crystal Sphere is marked [on the inside] with the Stars, etc. of the local World Setting, and contains all of that Setting’s Stars, Planets, Moons, Comets, etc.
3). The Crystal Sphere is usually “Open”. This means that Divine Access [for Divine Magic, etc.] works, and that the Outer and Astral Planes can be accessed. It also means that Spelljamming, and Arcane Spellcasting work normally, as per their standard rules.
4). The Athasian Crystal Sphere, from what I have read, is a Closed Sphere. And it always has been. Thus, no Divine Access, no access to the Phlogiston for Spelljamming, no replenishment of Arcane Energy, and in general, an increasingly post-apocalyptic Setting where the despotism of The Sorceror-Kings reigns supreme, and desperation in life and struggle for survival are the order of the day.
5). Athasian “Divine Classes” such as the Athasian Cleric, or Athasian Druid, are gaining their Spells from the Land, and the Elemental and Natural Guardians thereof, rather than an external Planar source, like standard Clerics; The Templars of the various City-States gain the power directly from their local Sorceror King/Queen instead.
Hope all of this helps as an [unofficial] clarification.

Christopher Simpson.

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Throwing out a few ore tidbits: if one looks at the calendar of Athas (in ivory triangle boxed set), it is SUSPICIOUSLY tidy and even. Which kinda screams artificial. Of course it’s almost certainly to have been intended to make the writer’s job easier, but you could also say that the planet’s orbit is itself artificially regular, hence the tidy yearly calendar.

Also re: the crystal sphere, the old Nether boxed set for the Realms included a 12th level spell (i think it was 12th) with the sole purpose and effect of “closing” a crystal sphere. And the only crystal sphere to have EVER been stated as being closed is that of Athas. Draw your own (very obvious) conclusions.

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I’ve just looked up “Brown Dwarf” on wikipedia, and was redirected to REd Dwarf stars via https://en.wikipedia.org/wiki/Luhman_16 and thence to https://en.wikipedia.org/wiki/Stellar_classification
In this latter article, there is an extended Treatise concerning all forms of Stellar Classification, not just the traditional OBAFGKM [Mnemonic: “O, Be A Fine Girl, Kiss Me”; “Girl”, on account of the fact that, at the time, almost all Astronomers were men]. The article, under the heading of L-Class stars, tells that the largest of these Stars are capable of fusion, but they are very cool, radiating mostly in the Infra-red - their surface temperature is around 1100 degrees Centigrade or so. Such a star would look dull red, possibly crimson or brownish, and the Habitable Zone would be very close to the star, making it [the star] appear large in the Sky.

An alternative set-up might be the “Falcons of Narabedla” / Darkover set-up [cf. the truly brilliant “Darkover” series by the late, great, Marion Zimmer Bradley]. This would allow for a Planet to orbit a really cool [temperature-wise] Red Giant star of some type. The only problem here is that the cooler the Giant Star, the larger it is, and thus the dramatically longer it takes for a planet to orbit it.

It should also be noted as a parallel, that Oerth [the Planet of Greyhawk, Blackmoor, and Kara-Tur], has two dissimilar-sized Moons, just like Athas. Is Athas a late [and possibly Alternate Prime] version of Oerth?

Christopher Simpson.

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Oerth’s system is explicitly stated to have the sun orbit Oerth. Just tossing that out there. And the Dark Sun logo clearly shows Athas as an itty-bitty in comparison to its star.

Also, Kara-Tur is the far eastern coast of the Forgotten Realms.

I have always gone with a main sequence star similar in size and mass as our sun.

Scientifically speaking, when you start to mess with the mass of the star that a planet orbits it, changes the number of days the planet takes to go around it. (The mass of the planet orbiting It can largely be ignored. Although Athas seems to have Earth type gravity because It operates normally)
It also depends on the distance the planet is from the star. The closet you make it, the smaller the star has to be.
I happen to like a 365 day year. Which is what Athas has. IIRC… Or close to it.
This can all be calculated using Kepler’s third law. I found a handy tool that lets you plug in different values.


Set the semimajor axis units to “au” (Astromic units i.e. Distance from earth to sun) then set this to 1. Any other value is just a multiple of fraction of the earth distance. Finally set the orbital period units to “days”
If everything is set to 1 you should get close to 365 days.

I prefer to think of the problem with Athas is that the sun has started to enter the stages prior to entering the red giant phase. Here is a website that discusses this happening in the future of our planet.

I’m not quite sure how to explain the blue age unless it was more of an atmospheric impact making the sun look blue. Or maybe just magic does everything and all the physics can be ignored. :wink:

[quote=“Rovewin, post:11, topic:2165”]
I’m not quite sure how to explain the blue age unless it was more of an atmospheric impact making the sun look blue. Or maybe just magic does everything and all the physics can be ignored.[/quote]

It is possible the power that changed the sun also moved Athas to an appropriate distance from the sun, to stay in the habitable zone. I personally believe the Athasian sun in a red dwarf, as they release a lot more heat than red giants. Also, the old logo that showed Athas in comparison to the sun showed Athas as rather large compared to our sun and Earth.
Also, a planet orbiting a red dwarf would have to be closer to the star, which would make it appear huge in the sky.

I previously liked the idea of Athas being closer to the star it revolves around making the sun look HUGE. (including a revolving around a red dwarf) until I started looking at the physics and the equations surrounding it. (For those that like the physics to all work out)

One problem that creeps up with a red dwarf is that they range from like 7.5% to no more than 50% of the mass of the Sun. If you use a mass of .5 suns and if you keep the orbital period of Athas at 375 days, the equation forces the planet to be at about .81 times the distance of earth to the sun. So now you are 19% closer to the star, but it is 50% of the mass of the sun. Not likely to look larger. Red dwarves also burn cooler than the sun. See https://www.space.com/23772-red-dwarf-stars.html

This is why I just figured using a sun like star that was turning into a super giant. The mass could still be similar to the Sun’s but that it had expanded, -its volume had increased- without increasing its mass. Which is what happens in red giants.

The other thing to consider is that the calendar of Athas has been used for some 14500 years. The calendar started sometime in the blue age at year 1. By year 8 the blue age ended bringing in the brown tide. During this time, and into the “current” year, the calendar maintained 375 days for each year. If the planet has moved closer or further away from the sun as a result of magic it would have modified the number of days in the year.

Good points.

The science doesn’t seem to work for the star to change in size. The mass would have to remain about the same for all of the stars phases, or the orbit would change, as you correctly pointed out. But that would mean the actual size could change very little, or Athas would move out of the habitable zone.

Given that the year is longer, but Athas is warmer and has a red, cooler star, it would probably mean that Athas has a thicker atmosphere than Earth to retain heat. A red giant star would engulf Athas and a red dwarf is too small.

Sadly, I don’t it’s possible to classify the Athasian sun, as I understand stars. Is it possible to get astrophysicist in here?

Maybe we are thinking too narrowly.

What if it isn’t the star or planet so much as it is the space in between? What if the events could be explained by a large artefact lens device in space between Athas and the Dark Sun designed to capture more solar output and focus it on Athas? Could explain a lot of things, perhaps…

The original intent might have been to provide more power, but a slight misalignment, and sizzle goes the planet.

Also remember (and this is a biggie to me in my own attempts to justify setting details after the fact) that when Rajaat briefly broke free in the Cerulean Storm, the sun literally changed back to a blue star.

Although perhaps this was just a localized effect to Ur Draxa. I would think that if it weren’t then everyone on the planet would have a freak out and all sorts of cults and religious movements would crop up based on “That time the dark sun turned blue for an hour or so.”

Although also perhaps that was just a detail that escaped the setting handlers’ minds when they started working on the revised setting.

But really, it seems kind of a major thing: Rajaat literally seemed capable of backing up his check writings with an actual return to the Blue Age, and the start literally turned blue again.

That’s not a small detail.

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If you allow for space halflings, you could also allow for a giant lifeshaped disk that focuses the light of the sun.

As part of the plan to increase the yield of the ocean the most ambitious life shaped creation ever conceived involved a space based lens, the pristine tower and an obsidian sphere to control it all.

Rajaat was able to change a small parts of the lens back to its original clear coloring which allowed the sun to look blue in the valley of dust and fire but was prevented from changing the entire lens back to its original intended color. These changes require massive amounts of energy absorb to the lens and focused on the pristine tower in conjunction with energy gathered from the world and fed back into the tower.

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