Merchant’s Calendar Readme: Lore Unlooked For

The great thing about 2nd edition was that there was a great focus on the lore of the campaign worlds. So much so that some supplements were completely dedicated to it. J.R.R. Tolkien explained this phenomenon best in “Unfinished Tales”:

It is, I suppose, a tribute to the curious effect that a story has, when based on very elaborate and detailed workings, of geography, chronology, and language, that so many should clamour for sheer “information,” or “lore.”

And so we find the likes of The Ivory Triangle, Veiled Alliance, and Elves of Athas describing the world in so much detail there few rules to be found in them. The Ivory Triangle especially expounded on a specific region of Athas in enough detail that it came in boxed set form. Of particular interest in Ivory Triangle was the description of how Athasians measure time using the Merchant’s Calendar.

Using both the Ivory Triangle resource and the description of Athasian years in the original campaign setting boxed set, Dave Ries-Clark developed an application in 2000 to track dates and moon phases on Athas. The Merchant’s Calendar application is excellent not only for its adherence to the Dark Sun canon, but also the inference of other aspects of Dark Sun cosmology using worldly astronomical principles. Due to the level of detail of the below reasoning, one might infer that Dave Ries-Clark is employed in the field of astronomy or astrophysics (he is a programmer with a gift in astronomy). These exceptional details are explained in the application’s read me file. Since the application is old, it is feasible that it will be unable to run in the future. Since the general calendar information can be recreated with Dark Sun sourcebooks I predict the information in the read me file will be more interesting as time progresses. For the sake of posterity and an interest in the brilliance of the read me file I will post the more vital cosmological points here with added links and my comments:

Latitude and Longitude

This program does not currently allow for customization of latitude and longitude of the observer’s location. This isn’t a big issue, since most of Athas isn’t even mapped. Longitude poses the biggest problem, since what is visible in the sky depends on where you are on Athas. Latitude would have a lesser effect in that latitude will determine the length of the day and how low Low Sun got and how high Highest Sun got. But, since Athas is tilted on its axis less than the earth is, it really isn’t going to vary that much. Unfortunately we can’t even assume that the Tyr region is in the northern hemisphere based on the seasons, since Highest Sun would be Low Sun in the southern hemisphere (and vice versa). Consequently, seasons are no real indication. This gives us a little freedom in determining these things.

I would like to suggest that Ur Draxa be the marker for 0 degrees longitude, although the entire Tyr region is probably in the same time zone. With that in mind, if you were west of the Tyr region (like, way out in the boonies of the Crimson Savannah) you would see the Ral/Guthay conjunction earlier in the evening, as opposed to at midnight if you were in Ur Draxa. Future versions of this program may eventually allow latitude and longitude settings.

Highest Sun and Low Sun

Highest Sun

Highest Sun (as the actual event) occurs at midnight on Dominary 1, the exact start of the new year. It is termed “Highest Sun” to avoid confusion with the season “High Sun.” The Highest Sun holiday is considered to be the whole of Dominary 1st. Really, though, the dark sun is so imperceptibly lower at 12 noon on Dominary 1st than it was earlier at 12 midnight (on the other side of Athas) that it just doesn’t matter.

Low Sun

Low Sun occurs at noon on Morrow 3 (as opposed to midnight of Morrow 1 as implied in the Dark Sun boxed set and “The Ivory Triangle” boxed set). My reasoning for this is that Noon of Morrow 3 is the exact middle of the Athasian year. Since the boxed set indicates that the year begins with Highest Sun, it stands to reason that the exact middle of the year is Low Sun. However, as above, the difference in 12 hours time is basically imperceptible, so nighttime ceremonies for Low Sun are justifiable.

Ral and Guthay

Ral and Guthay’s Orbital Periods

Ral and Guthay’s orbital periods are not mentioned in any Dark Sun product that I know of, but given that they only meet in the heavens as full moons once every 11 years, I determined that the most likely periods were either 55 days for Ral and 75 days for Guthay or 33 days for Ral and 125 days for Guthay. However, I quickly found that the former periods repeated too soon, with Ral and Guthay meeting as full moons every 3 2/3 years. That left Ral at 33 and Guthay at 125, moving like clockwork to only meet full once every 11 years (they also meet as new moons midway through the Endlean Cycle). Pseudo-fact: Ral rises 43.64 min later each day. Guthay rises 11.52 min later each day. This assumes that the moons orbit in the same direction as Athas spins, which is most likely.

geneome note: This is a brilliant deduction. The 11 year period could have been pulled out of thin air by TSR employees (namely Tim Brown), but now we have new “lore” conforming to a line item in the setting. That’s the best kind of new information: in depth and conforming to present canon despite these details likely never being considered.


Eclipses are very briefly addressed (one sentence) in the [original] and [expanded]. boxed sets. From the [original]: “The endlean cycle is complete when Athas’ two moons, Ral and Guthay, meet in the heavens, a major eclipse that occurs once every 11 years.” Unfortunately, it does not say whether the moons are full or new (for that matter, I wonder if the author really meant “conjunction”). However, since the King’s Age begins and ends with the moons meeting in the heavens, I think it is safe to assume that they mean full moons, since Ral and Guthay meeting as new moons would put the start of the King’s Age at noon on Dominary 1st, kind of an odd time to start the King’s Age.

There are other reasons for having the full moons in conjunction start the King’s Age. For example, with the above scheme, the festival weeks Dessalia, Assalia, and Zenalia all would end on the 5th night with Guthay reaching full illumination–sort of ending the 5 day party with a bang! BTW, notice that the names of the festival weeks correspond to the season…Dessalia/Sun Descending, Assalia/Sun Ascending, and Zenalia/High Sun [or Zenith].

geneome note: I concur with the idea that the authors meant a conjunction of full moons. The former being clear from the way the above sentence from the boxed set is worded and the latter just being more in line with our perception of moons in that they are a bigger deal when full along with the thinking noted in the read me.

The Endlean/Seofean Cycle

The Endlean Cycle

The Endlean Cycle is based on the movement of the Moons, so the moons are always in the same positions as they were 11 years earlier. The start of the Endlean Cycle begins and ends with the conjunction of the two full moons Ral and Guthay. I have placed this conjunction at 12:00 AM on the first day of the Endlean Cycle, the exact moment when Ral passes Guthay in the sky.

The Seofean Cycle

The Seofean Cycle is based on a more abstract movement cycle. Originally, with the beta version, I was thinking that this cycle was determined by a “wobble” of Athas’ axis. The earth has such a wobble, but is many thousands of years in cycle. However, since then, I have rejected that idea. 7 years is just not long enough for an axis wobble. I have a new theory though…actually two new theories, either of which could be used.

The first is the “Other Planet” theory. This would be a large, possible gas giant with an orbital period around the dark sun of 7 years. (Jupiter has an orbital period of around 12 years, so this is not unreasonable.) This planet would pass through the same constellations in a 7-year cycle (as viewed from Athas). The only problem with this theory is that there are already 12 constellations that are associated with the months. For the planet theory to really be solid, the names in the Seofean cycle would have to correspond to 7 constellations.

The second is my more recent theory, and as such does not have nearly as much thought into it. Our own sun has a solar cycle which repeats every 11 years. It is based off of solar activity and measured by monitoring the number and frequency of sunspots. It could very well be that the dark sun has a similar cycle (of 7 years) that is detectable by Athasians. Incidentally, there is some very interesting data regarding events on earth and the solar cycle.

geneome note: Dave originally noted in his read me in regard to his second theory of the Seofean cycle that it might be due to a saros cycle. Since the solar cycle is 11 years long, related to sunspots, and has effects on Earth, I changed his paragraph above to mention and link to the solar cycle rather than the saros cycle.

It stands to reason that the early inhabitants of Athas would first notice the cycle of the moons before looking to the positions of planets or the solar activity of the dark sun. Therefore, I believe the Endlean Cycle was established first. This is also reflected in the fact that the Endlean portion is said first when stating a years name on present day Athas. As the years passed, no doubt sages noted the basis for the Seofean cycle (whatever that may be) and soon documented a second, swifter cycle, though not so dynamic as the moons, and so the Seofean cycle was born.

geneome note: If the seofean cycle was created during the Blue Age (or even the Green Age) it would be quite possible that more advanced astronomical observations would have been possible.

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