ASTRONOMY IN EAST AFRICA
The Borana-Cushitic Calendar and Namoratunga
Laurance Reeve Doyle
Space Sciences Division, N.A.S.A.
Ames Research Center, Moffett Field, California
"While Western thought has always prided itself on scientific objectivity, it has often been found unprepared for such surprises as an intellectually advanced yet seemingly illiterate society. In the face of apparent primitiveness, the possibility of significant intellectual development may not be fully investigated.
This was certainly the case when, in the early 1970’s, Dr. A. Legesse first found that the Borana people of southern Ethiopia were indeed using a sophisticated calendrical system based on the conjunction of seven stars with certain lunar phases. Previous calendrical investigations into the area up to this time had superficially stated that the Borana "attach magical significance to the stars and constellations," incorrectly concluding that their calendar was based, as ours is, on solar motion.
What Dr. Legesse found was an amazing cyclical calendar similar to those of the Mayans, Chinese, and Hindu, but unique in that it seemed to ignore the sun completely (except indirectly by way of the phases of the moon). The workings were described to him by the Borana ayyantu (timekeepers) as follows.
There are twelve months to a year, each month being identifiable with a unique (once a year) astronomical observation. The length of each month is either 29 or 30 days – that is, the time it takes the moon to go through all its phases. (This time is actually 291/2 days and is called a synodic month, but the Borana only keep track of whole days). Instead of weeks, there are 27 day names. Since each month is 29 or 30 days long we will run out of day names about two or three days early in the same month. The day names can therefore be recycled and for day 28 we use the first day name again, the second day name for day 29, and start the next month using the third day name. Thus each month will start on a different day name. Whether the particular month is to be 29 or 30 days long would depend on the astronomical observations, which are quite ingeniously defined.
The seven stars (or star groups) used to derive the calendar are, from northernmost to southernmost, 1) Beta Triangulum – a fairly faint navigation star in the constellation of the Triangle, 2) Pleiades – a beautiful, blue star cluster in the constellation of Taurus the Bull, and sometimes referred to as the seven sisters, 3) Aldebarran – a bright, red star that represents the eye of Taurus, 4) Belletrix – a fairly bright star that represents the right shoulder of the constellation Orion the Hunter, 5)Central Orion – the region around Orion’s sword where the Great Orion Nebula may be found, 6) Saiph – the star representing the right knee of Orion, and finally 7) Sirius – the brightest star in the night sky and the head of the constellation Canis Majoris, the Great Dog.
The New Year begins with the most important astronomical observation of the year – a new moon in conjunction with Beta Triangulum. (this day is called Bitotesa, and the next month is called Bitokara). The next month starts when the new moon is found in conjunction with the Pleiades. The third month starts with the new moon being observed in conjunction with the star Aldebarran, the next with Belletrix, then the area in between Central Orion and Saiph, and finally with the star Sirius. So the first six months of the calendar are started by the astronomical observations of the new phase moon found in conjunction with six specific locations in the sky marked by seven stars of star groups.
The method is now switched and the final six months are identified by six different phases of the moon (from full to crescent) being found in conjunction with only one position in the sky – the one marked by Beta Triangulum. Thus the whole Borana year is identified astronomically and when the new phase moon is again finally seen in conjunction with Beta Triangulum the New Year will start again. Since there are 12 such synodic months of 29 ½ days each, the Borana year is only 354 days long.
Now, in the latter part of the 1970’s another interesting development was to take place regarding the astronomy of this region. In 1977 Drs. B.M. Lynch and L.H. Robbins, who were working in the Lake Turkana area of northwestern Kenya, came upon what they believed was the first archaeoastronomical site ever found in sub-Saharan Africa. At Namoratunga, it consisted of 19 stone pillars, apparently man-made, that seemed to align toward the rising positions of the seven Borana calendar stars as they had appeared quite some time ago. (their suggested date from the various archaeological considerations, which still requires corroboration, was about 300 BC). Due to precession (the slow, wobbling of the pointing direction of the rotation axis of the Earth), the stars will seem to move from their positions over the centuries, although the moon’s position would not vary on this time scale. (Such an example is the alignment of certain features of the Egyptian pyramids with the star Thuban in the constellation Draco the Dragon, which was the north polar star about 5000 year ago; today it is Polaris and in several thousand years it will be Vega). If the date that Drs. Lynch and Robbins suggested was correct, the site would then correspond to the time of the extensive kingdom of Cush, referred to as Ethiopia in the Bible but actually centered about present day Sudan. One would then conclude that the Borana calendrical system was old indeed, having been developed by the Cushitic peoples in this area about 1800 years before the development of our present day Western Gregorian calendrical system.
In 1982, a number of significant questions arose concerning the site, the calendar, and archaeoastronomy of East Africa in general. The pillars were remeasured by an anthropologist in Kenya (Mr. Robert Soper) and found to be magnetic in nature. The original measurements had to be modified but, again, alignments with the seven Borana stars were found. However, this brought up the question of whether pillar alignments are significant at all, since the Borana ayyantu certainly can recognize the phases of the moon and when it is in conjunction with the appropriate seven stars. It was time to approach the question astronomically, and ask the moon and the stars how the calendar worked.
First, we could take the New Year’s observations, a new moon in conjunction with the faint star Beta Triangulum. What is meant by the term "conjunction" which is astronomically defined as the closest approach between two celestial objects? A new moon means that the moon is very close to the sun, being at best only a very small crescent, and therefore can only be seen just before sunrise or just after sunset. Interestingly enough, it turns out that during this twilight time the sky is too bright to be able to see the star Beta Triangulum so that seeing the new moon next to Beta Triangulum, the most important observation of the Borana calendar, was impossible!
In addition, assuming that the new moon and Beta Triangulum could be somehow seen rising together, the next month’s new moon rises significantly behind Pleiades, the newt conjunction star group. The third new moon rises with Belletrix, having skipped the third star, Aldebarran, completely. This is certainly not how the Borana described their calendar. If we were to continue to try to work the calendar in this way, by the start of the sixth month the new moon would be rising almost four hours after Sirius.
How could the calendar work then? Suppose (as we did), that one takes the term "conjunction" to mean "rising at the same horizon position" instead of "rising horizontally next to at the same time." Thus one could mark the horizon rising position of Beta Triangulum, with pillars for instance, and once a year a new moon will rise at that position on the horizon. Let us suppose that this astronomical event marks the start of the New Year. We must add that we are taking the horizon rising position of these seven stars as they were in or around 300 BC, since present day Beta Triangulum has precessed too far to the north over the centuries and the moon will never rise there. However, the position of 300 BC Beta Triangulum, as well as the other Borana stars, was quite within the realm of the moon’s orbit.
Now where will the next new moon rise? It turns out to rise at precisely the rising position of Pleiades! The next new moon, marking the start of the third month, rises at the Aldebarran horizon position, the next at Belletrix, the next in between Central Orion and Saiph, and finally the sixth new moon rises at the horizon position that Sirius rose at during the night. During the next six months one can tell what month it is only in the middle of the month, since one has to wait to see what phase the moon is in when it appears at the Beta Triangulum horizon position. During the seventh month, as described, a full moon will be observed at the Beta Triangulum position. The next month a gibbous waxing moon, then a quarter moon, and successively smaller crescents will be seen there until, at the time when the 13th or first month should start the new year again (exactly 354 days later), a new moon is again seen rising at the Beta Triangulum position on the horizon.
It is interesting that one can draw some significant anthropological results from the astronomical derivation of this calendrical system. It would appear that the calendar would have had to have been invented (to use the stars correctly) sometime within a few hundred years of 300 BC, a time when the Cushitic peoples were dominant in this part of the world. Hence we would call it the Borana-Cushitic calendar. In addition, although the seven Borana-Cushitic stars no longer rise in the correct horizon positions to be correctly marked by pillars for observing the monthly rising position of the new moon, the present day Borana people nevertheless use this system of timekeeping. The implication is that the Borana require ancient horizon markers in their present derivation of the calendar.
Concerning the site at Namoratunga, and considering that the use of pillars is apparently necessary to the derivation of the calendar, such horizon markers as are found there may, indeed, have been an ancient observatory. Petroglyphs on the pillars at Namoratunga may also hold the possibility of being ancient and, if Cushitic, may represent the alignment stars or moon. Cushitic script has never been deciphered and any hints as to the meaning of tits symbols could be significant clues with very exciting prospects indeed!
Thus, archaeoastronomy in East Africa is still quite new and many discoveries await. From coming to understand, even in a small way, the calendrical reckoning and observational abilities of the ancient and modern astronomer-timekeepers of this region, Western thought should certainly not again underestimate the ingenuity and intellect present there. As for this Western thinker, this study continues to be a welcome lesson in perspective and humility, taught to him by his astronomical colleagues of long ago."
This is a summary of a talk delivered at Caltech for Ned Munger’s African Studies class.http://www.tusker.com/Archaeo/art.anthroquest.htm