Is Athas tidally locked to its Red Giant?

The maps that I have seen of Athas only show half of the planet. I am wondering if Arthas is tidally locked since the Red Giant is so close.

If this were the case it is possible that there is a very cold dark side of Athas, Which creates another even crazier aspect to the campaign setting that has never really been explored.

1 Like

I’m no expert, but if athas is locked that way, then there wouldn’t be any day and night cycles since the planet isn’t revolving around its own axis.
And since we know for a fact that day and night cycles exist on athas, we can be pretty sure it isn’t locked.

That being said, nothing stops you from deciding that that is how thing are in your game. The dark side of athas is a very interesting idea


Some elves believe Athas is flat (from Dragon Kings short story)… if that’s true I wonder if there’s some strange way to rework the cosmetology? Sorry, not really thinking 3 dimensionally today.

1 Like

That is a valid point, but since the Planet has 2 Moons(which is another post in itself), maybe the “night” is actually just one of the moons causing an eclipse?


Interesting suggestion, but it will still look like an eclipse and not a true night, wouldn’t it?


That would depend on the size of the moons, their proximity to Athas, and Athas’ proximity to the Red Giant. Another factor to consider is phases, if the moons move very quickly around Athas there would be few phases. I haven’t studied the Cosmos around Athas enough in depth to answer that.

Killer_DM, The idea about the world being flat is interesting, but that would still leave another side on the back side of the flat disk. The other side must have something on it.


Blockquote[quote=“Jason_Goff, post:6, topic:2657”]
That would depend on the size of the moons, their proximity to Athas, and Athas’ proximity to the Red Giant. Another factor to consider is phases, if the moons move very quickly around Athas there would be few phases. I haven’t studied the Cosmos around Athas enough in depth to answer that.

I have studied this. A lot. I have spent days plugging the calculations in for different orbital periods for the moons along with varying distances, sizes, and masses all to make it work according to how real physics works.

I think Athas isn’t too different than Earth size wise. The mass is about the same. Other wise gravity would operate differently. (All rules treat gravity as normal)

Distance from the sun is a little more giving 375 day orbit vice 365.25.

Moons have to have orbital periods that result in an eclipse every 11 years. Or 4125 days. I’m am in agreement with Agantyr the maker of the Merchant Calendar program. (Find this in the athas site.) he uses 125 for Guthay and 33 for Ral.). Though other combinations could work. I think 125 and 33 work best.

If you are interested in the moons of Athas check out my info here:

There isn’t a way under physics that I am aware of would allow one of the moons to be causing the night. Day/night is the planet simply rotating on its axis. Moons do cause eclipses.

The major one mentioned in the rule book happens at the first day of the year which is also at High Sun, the summer solstice. This eclipse is really a conjunction of Ral passing in front of Guthay when they are both full. So they are on the opposite side of the planet from the sun. I would assume they also pass thru Athas shadow as well turning them red color.

But what is often overlooked is the other eclipse that also happens every 11 years, but 5.5 years later at Low Sun when both moon are new and cross the face of the sun.

Depending in the apparent size of the moons and sun this may look like two black circles crossing the sun blocking light partially. Or blocking it completely like a regular solar eclipse.

I highly recommend you download the merchant calendar program and play around with it.

My two ceramic pieces.


As others have mentioned, a tidally locked planet won’t ever experience day/night cycles, though a moon of a planet would (the “dark side of the Moon” is a misnomer. The hidden side of our Moon sees plenty of sunlight). A ltidally ocked body still rotates though, with a full rotation being the same as an orbital period.
If the Earth didn’t rotate at all then your location would have a “day” of about 91 days and a “night” of about 273 days, as a quarter of the planet would be exposed to the Sun at any given time (ignoring variances from the tilt).

A moon being the source of a day/night cycle on the Tablelands of a tidally locked Athas would be very strange. First it would have to complete the orbit around the planet during the daytime (so extremely fast). Then it would have to slow down to a crawl during the night time to provide a full night’s darkness and it would have to be massive to blot out the sun across the entire Tablelands. Of course the rest of the planet wouldn’t have any noticeable night time at all as it zips across the sky.

This is all boring science stuff though, which noone in a fantasy setting is beholden to. Who’s to say that the Sun isn’t a gate to the elemental plane of fire that a god/King Tech closes during the night?


The best comment here is the planet size.

So many people think that Athas is small (mainly because of the scale of the Tablelands). But if it’s Earth-sized, then there could be a few hundred dragons, small oceans hidden here-and-there, and pockets of civilization at different tech levels across the globe (or circle if it is indeed a flat Earth).

1 Like

Thank you for that answer, so I get from your statement that either we have a flat disk, or the other side of Athas is just not mapped.

Good points. I will make a post discussing the moons after this one. I am interested in adventures there, I remember reading about gates that take you to them, somewhere. Like the gate in Mystara that connects to it’s moon.

Starsage already opened a discussion about the moons, so check it out


Thanks, I will check it out.

I go with a sphere. Just like Earth. And roughly similar in size. The other side is not mapped in canon. I don’t think any evidence supports it being a flat disk. But hey, your world.