Ancient African Skies (Archaeoastronomy In Kenya)

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Ancient African Skies

By Laurance R. Doyle
The SETI Institute
posted: 07 April 2005
07:07 am ET

"Bwana! That must be it!" I pointed back over my right shoulder at some man-sized stone pillars off on a rise from the dirt road we were driving on. The road would be described by Kenyans as "corrugated" meaning that we had to get out in some places to look for it on our way to the Turkana region—not too far from where the most ancient hominid fossils had been found by Richard Leakey, Director of the National Museums. We had heard of an ancient astronomy site in this region made up of basalt pillars that were magnetic, so needed to be remeasured using something other than compasses. Eddie Frank, of the Tusker Trail Company, some students from various places in the U.S., and I had come to do just that. We had camped with hippos at Lake Nivasha, swum in Lake Turkana known to have over 3 million crocodiles in it, watched as several million pink flamingos had taken to the air around Lake Nakuru, and seen the migration of a couple million wildebeests across the Masaai Mara plains, all on our roundabout safari to this ancient astronomy site.

The pillars were known as "Namoratunga" or "stone people" in the Turkana language. They had been said to have been built for an astronomical purpose, to reckon the Borana calendar, and were reputed to be a couple of thousand years old. They had petroglyphs on them, some matching the ancient property symbols of the Kush, a people of the Sudan who had once conquered Egypt (in the 8th Century B.C.) and whose language has yet to be deciphered. From maps of ancient Kush, I knew that the front of almost all their pyramids appeared to face the star Sirius, which has not changed its position in the sky very much for the last several thousand years.

We had a description of the Borana calendar, but this did not make astronomical sense. For example, the new year of the Borana calendar was said to occur when the star beta Triangulum was "in conjunction" with the new moon (new, give or take a couple of days). A new moon is, of course, close to the sun (i.e., a thin crescent), and consequently found in the twilight sky. However, the star beta Triangulum is a 3rd magnitude star and could not been seen in twilight. Thus, we could not even get the Borana new year started according to the description we had from anthropologists.

We made camp under some acacia trees and the next day tramped over to the ancient site. It was obvious that the stone pillar had been polished by the wind over a long time. We used navigational sextants to measure the angles between each pillar from the others, and a measuring strip to map the interdistances between them. The day was blessedly cloudy—the first such day in the Turkana desert we had seen. We sketched the petroglyphs on each of the pillars as well. And Matunga, our cook, brought us all lunch at the site with some very good Kenyan tea.

Sitting among the pillars it occurred to me that perhaps the translation of the word "conjunction" might have been incorrect. What had been taken to mean "rising with" on the same place on the horizon, might instead mean "rising single-file after." Humm, that could account for having pillars also line up with the stars and the moon. There are seven special Borana calendar stars that define six places in the sky. The Borana calendar stars are: beta Triangulum, Pleiades, Aldebaran, Bellatrix, central Orion and the star Saiph taken together, and Sirius. Well if the single file idea was correct, then at the beginning of the Borana year the star beta Triangulum would rise—mark the place with a pillar, for example—and then at dawn, the new moon would rise in the same location on the horizon. (We were at 3.4 degrees north latitude, so the stars there rise almost vertically—actually 3.4 degrees off the vertical to be exact.) However, this vertical single-file "conjunction" also would not work because (here very close to the equator) the star beta Triangulum was rising about 35 degrees north of east but the farthest north the moon ever got (in its 18.6-year cycle called "regression of the lunar nodes") was 28.5 degrees north of east. So, again, the calendar could not even get started. What kind of a calendar was this, I thought? When we had met with the scientists at the National Museums of Kenya they also did not know how the calendar worked. Yet the Borana are practical people; they would not have made up an apparently ancient calendar that didn’t work.

Ah, ancient! I knew that while the star Sirius had not moved much, many of the stars had altered their apparent position on the sky (this "precession" is due to the wobble of the Earth’s rotation axis over a complete circle on the sky every 26,000 years). During the time the first pyramids in Egypt were built, the North Star was not Polaris in the Little Dipper, but Thuban, in the constellation of Draco the Dragon. This is where several openings in the great pyramids were aligned. The Namoratunga site was said to possibly be as old as 300 B.C. based on some carbon dating of bones. We precessed the Borana stars then back to 300 B.C., and some "moved" quite a bit. But where was beta Triangulum in 300 B.C.? Before I answer that question, let’s take a quick look at how, actually, the Borana calendar is supposed to work.

There are no weeks in the Borana calendar (our 7-day week only comes from the seven ancient planets that appeared to circle the Earth—Sun, Saturn, Moon, then in English a switch to Norse gods—Oden, Thor, and so on). The Borana have 27 day names, and 12 (lunar) month names. The first day of the new year starts on the day name "Bitto Tessa" on the month "Bito Kara." (This is when Triangulum is in "conjunction" with the new moon.) One then simply counts the day names through the month based on that first astronomical observation—conjunction of the new moon at the beta Triangulum position. The description continues; one will know that the next month begins when the new moon is "in conjunction" with the next star or star system, in this case, Pleiades (a blue star cluster). This occurs 29.5 days after the start of the first month. That means that one runs out of day names a couple of days early. This is OK, and the names of the days that started the month are also the names of the days that finish the month. (This is the same for all the months, adjusted for the observations, of course, allowing a variation of a day or two here and there based on the astronomical observation.)

The third month starts when one spots the new moon rising "in conjunction with" the star Aldebaran, and so on down the list of six Borana star positions for the first six months. Why does this work? It is because the "sidereal month" (time for the moon to move from a certain star position back to that position again—27.3 days) is not the same as the "synodic month" or the time it takes the moon to go from a particular phase (full-moon to full-moon phase, for example) back to that phase again (29.5 days). The synodic month is longer because the Earth has orbited the Sun just a bit also in a months time and the moon has had to (sort of) "catch up." That is, when the moon arrives at the same place again (star position), the Earth has moved a bit farther and so to align with on the exact opposite side of the Earth from the Sun (same lunar phase again) the moon has to travel a bit farther. (Try this if you like with three people, one the moon, one the Earth, and one the Sun, with the Sun shining a light onto the others they move around the Sun and Earth, respectively; see what happens.)

So, back to the 300 B.C. positions of the stars—would the calendar work if we put the stars back to the same time as the pillars were expected to have been put there? Indeed, the second new moon rose at the exact place where Pleiades used to rise in 300 B.C.! An exciting moment! The next new moon? It rose at the 300 B.C. position of Aldebaran! The next? Bellatrix! The next? In between central Orion and the star Saiph! And finally the 6th new moon of the year rose where the star Sirius rose (and still rises) on the horizon! It worked in 300 B.C.!

Well, it looked as if we had deciphered an ancient calendar! The next six months of the year are defined by a switch of the moving parts. Instead of the horizon location changing, the next six months are defined by the various phases of the moon rising at the Triangulum only position (and therefore one can only check the calendar in the middle of the month). But this all worked too. One goes through the full moon, three-quarter (gibbous) waning moon, quarter waning moon, large crescent waning, medium crescent waning, and finally small crescent waning—all rising at the Triangulum position—until one is back to the new moon at the Triangulum position again and Happy New Year! (The exception is that every three years another month is added because the lunar year is 11 days short of the solar year—this is a kind of "leap month" the Borana folks use.)

So what about the 19 stone pillars that make up Namourantunga—are they indeed used for the ancient Borana calendar? We found that they made 25 alignments with the seven positions on the sky of the ancient Borana stars or star systems. After some calculations, we found that this many alignments could only have occurred randomly about 43 times out of 10,000 random star positions (counting the alignments with the pillars generated randomly by computer, and doing this test of randomly made-up star position 10,000 times for good measure). In other words, we found also that the pillars at Namoratunga—to have made as many as 25 or more alignments with the seven specific ancient positions of the Borana stars— would only occur randomly 0.43% of the time. From this mathematical experiment we could be about 99.57% sure that the pillars at Namouratuna had been build to do just that—line up with the Borana calendar star positions for 300 B.C.! And the petroglyphs on the pillars? The Turkana said they were ancient family names. This was interesting too, because a lot of them match the symbols on the pyramids of the ancient Kush people—symbols said to be royal property symbols. Perhaps the Kush also got as far south as they did north in ancient times. And perhaps petroglyphs might be a way (besides linguistics and genetics) to trace the migrations of ancient peoples.

As we began the long drive back to Nairobi I felt a quiet excitement. We had discovered a way of keeping time and one of the ways of thinking of some of the ancient African astronomers who had lived in the Turkana desert over two thousand years before. They looked at the sky and understood how it worked and, with the stars and moon as intermediaries, we had shared this special order with them across the millennia. We had read the same book of the sky together, and the practice of timekeeping that so often seems to separate us had, instead, this time brought us closer together.

Note: You can read a more detailed description of the Borana Calendar and Namoratunga at: http://www.tusker.com/Archaeo/articles.htm.

http://www.space.com/searchforlife/050407_seti_african.html

mal

 

[EnolaGaia]

The article quoted above includes the following:

Note: You can read a more detailed description of the Borana Calendar and Namoratunga at: tusker.com/Archaeo/articles.htm.

The posted link is dead. It led to a more detailed account of Doyle's findings and analysis of the Borana calendrical system. Here (below) is the text from the MIA online article from 2005.

Salvaged from the Wayback Machine:
https://web.archive.org/web/20050407175327/http://www.tusker.com/Archaeo/art.currentanthro.htm
-------------------------

The Borana Calendar REINTERPRETED

by Laurance R. Doyle

Physics and Astronomy Department, University of California, Santa Cruz,at NASA Ames Research Center, Space Sciences Division, M.S. 245-7,
Moffett Field, Calif. 94035, U.S. 20 XII 85​

The announcement of a possible first archaeoastronomical site (called Namoratunga II) in sub-Saharan Africa by Lynch and Robbins (1978) and its subsequent reappraisal by Soper (1982) have renewed interest in an East African calendrical system, the Borana calendar, first outlined in detail by Legesse (1973:180-88). I shall here reinterpret the calendar as Legesse describes it in the light of astronomical constraints.

The Borana calendar is a lunar-stellar calendrical system, relying on astronomical observations of the moon in conjunction with seven particular stars (or star groups). At no time (except indirectly by way of lunar phase) does it rely upon solar observations. The Borana year is twelve lunar synodic months (each 29.5 days long), 354 days. While it will not correspond to the seasons, this may not be of primary importance for people this close to the equator. There are twenty-seven day names (no weeks), and since each month is either 29 or 30 days long, the first two (or three) day names are used twice in the same month starts on a new day name. The day names are listed in Table 1, the month names in Table 2.

The first six months can be identified at the beginning of the month with a particular astronomical observation, whereas the last six months can be so identified only around the middle of the month. The first six months begin with the observation of the new-phase moon in conjunction with six positions in the sky marked by seven particular stars or star groups. Thus the phase of the moon is held constant while its position varies. The last six months are identified by a particular-phase moon seen in conjunction with the first star position. Thus, here, the lunar phase changes and the position is held constant. The seven stars or star groups in order are Triangulum (which I take to mean Beta Trianguli), Pleiades, Aldebarran, Belletrix, central Orion (around the sword), Saiph, and Sirius. They are given in Table 2 next to the months they define.

The New Year starts with the observation of the new moon in conjunction with Beta Trianguli. (The term "new moon" here will be taken to be within two days of zero phase, although the Borana allow up to three "leap" days’ leeway, the astronomical observation determining the correct day to start on. This is indicated in the day nomenclature by the assignment of like prefixes to two or three day names before the approximate time an important astronomical observation is to take place.) Since the new moon can be seen only just before sunrise or just after sunset, twilight makes the observation of Beta Trianguli (a third-magnitude star) in conjunction with a new moon impossible with the naked eye.

Assuming that such an observation, however, was possible, would the next new moon be in conjunction with the next star group. Pleiades? (Conjunction here is taken to mean "rising with" or "setting with," having the same right ascension. Legesse says (p. 182), "Let us assume that a new moon was sighted last night and that is appeared side by side with the star Sirius, which the Borana call Basa.") Since the sidereal period of the moon is 27.3 days long, it will arrive back at the Triangulum position more than two days before completing its synodic month. At the sidereal rate of 13.2° per day, the moon will be within 3° of Pleiades when it rises in the new phase again. However, by the time of the third month it rises, not with Aldebarran, the next star, but a little past Belletrix, the fourth star, which is supposed to start the fourth month. By the fourth month the new moon is rising past Sirius, the sixth start, and the calendar is clearly not working as described. It should be added that the right-ascension positions of the stars in the area from Beta Trianguli to Sirius change with time, at the rate of roughly 15° every thousand years. However, the stars stay in approximately the same configuration, and arguments based on their present right-ascension relationships will hold over the past several thousand years as well.

What happens if we take the term "conjunction," or "side by side," as Legesse has it, to mean not "rising with" but "rising single-file," that is, at the same horizon position (in other words, having the same declination)? Examining the idea that it is not the proximity of the moon to the star that is important but its horizon rising (or setting) position with respect to that star’s horizon rising (or setting) position, we immediately find that the first necessary observation, the new moon rising at the horizon position of Beta Trianguli, is not currently possible. Beta Trianguli rises (at the equator) about 35° north of the east point (0° declination), while the moon (on the northernmost average) rises at 23.5° north of east, never rising farther north than 28.5° from the East Point. The earth’s rotation axis is known to precess over the centuries, and while this does not change the lunar orbital positions significantly, it does change the apparent position of the stars. We can calculate the positions of the seven Borana stars at a time when Beta Trianguli was well within the moon’s declination limits to see if the calendar would have worked then. In 300 BC, Beta Trianguli was rising at a declination of +23° north of east. The right-ascension positions at the time still do not allow a "rising with" interpretation of the calendrical system. We can begin by defining the start of the Borana year as the new moon rising at the rising position of 300 BC Beta Trianguli. (The date of 300 BC was strongly suggested by the preliminary dating of Namoratunga II, but it was chosen because +23°, Beta Trianguli’s declination at the time, is the northern average of the moon’s monthly motion. I will take the moon’s motion, for the example here, from the Nautical Almanacs for 1983 and 1984.) The next new moon rises at 14° north of east, which corresponds precisely to the 300 BC horizon rising position of Pleiades, the next Borana star. The next four new moons (starting the next four Borana months) rise at +9 degrees, +1 degree, –11 degrees, and –17 degrees declination. These positions correspond to the 300 BC horizon rising positions of the Borana stars Aldebarran. Belletrix, central Orion—Saiph (taken together), and Sirius, respectively (Table 3).

The seventh month should be identifiable 14 or 15 days from its automatic start (about 29 days after the start of the sixth month) by a full moon rising at the Beta Trianguli position, and this is indeed the case. Each subsequent moon rises at this horizon position 27.3 days later (sidereal month) in a phase (synodic month) about two days less waxes (since it is on its way to the full phase again) each time. (Legesse has a waning moon, but this must mean waning with respect to each subsequent monthly observation, not with respect to the Phase State for that month.) On the thirteenth or first month, the moon is seen rising in the new phase again ("new" meaning within a couple of days of zero phase), and another year begins. Tracing the moon’s motion as it arrives at these positions in the sky (which are, however, no longer directly marked by the seven stars), we can derive the calendar (see Table 4).

This outline is still general with respect to what is sometimes called the lunar excursion (regression of the line of nodes of the lunar orbit). The three "leap" days the Borana calendar allows for the starting of some of the months just before an important astronomical observation could account for this declination excursion of the moon (± ca. 5° from 23.5° declination on an 18.6-year basis), but this would certainly require confirmation in the field.

The Borana calendrical system as described by Legesse is, therefore, a valid timekeeping system, subject to the astronomical constraints outlined here, and the pillars found in northwestern Kenya by Lynch and Robbins and preliminary dates at 300 BC could, as they suggest, represent a site used to derive that calendar. The calendar does not work in right-ascension sense, but it does work if taken as based on declination. It might have been invented around 300 BC, when the declinations of the seven stars corresponded to lunar motion as the calendar indicates, and the star names would therefore apply to the horizon positions as well. Because the horizon rising positions constitute the important observations (over half of which must be made at twilight), some sort of horizon-marking device would seem to be necessary. Since the calendar is still in use, and the horizon-making pillars can no longer be set up by aligning them with the horizon rising positions of these stars, it would seem that the Borana may be using ancient (or replicas of ancient) horizon markers and this possibility should be investigated. I look forward with great interest to a test of these hypotheses.

References Cited

Legesse, A. 1973. Gada: Three approaches to the study of African Society. New York: Free Press.

Lynch, B. M., and L. H. Robbins. 1978. Namoratunga: The first archaeoastronomical evidence in sub-Saharan Africa. Science 200:766-68.

Soper, R. 1982. Archaeo-astronomical Cushites: Some comments. Azania 17:145-62.

 

[EnolaGaia]

Here's the Wikipedia article about the site:

https://en.wikipedia.org/wiki/Kalokol_Pillar_Site