AST 309--Time
Dresden Codex Venus Table


The Dresden Codex is a Mayan book of astronomical predictions, in other words, an ephemeris. It is one of the very few Mayan documents to have escaped destruction by the Spanish invaders of the New World. Among the interesting things it contains are tables for the prediction of lunar phenomena and eclipses, and an elaborate ephemeris of the planet Venus.

The Venus Table of the Dresden Codex


The Dresden codex Venus Table consists of 5 pages, which are to be read in succession across a single line. After finishing with one line, the next line is read, and so on to the bottom of the thirteenth line of the table. Below I show a representation of the table in modern notation.

App 1-3 Di E Re W Di W Re E Di E Re W Di W Re E Di E Re W Di W Re E
Cycle 1 3:16 2:06 5:16 13:04 2:20 1:10 4:20 12:08 1:04 13:14 3:04 11:12
Cycle 2 11:16 10:06 13:16 8:04 10:20 9:10 12:20 7:08 9:04 8:14 11:04 6:12
Cycle 3 6:16 5:06 8:16 3:04 5:20 4:10 7:20 2:08 4:04 3:14 6:04 1:12
Cycle 4 1:16 13:06 3:16 11:04 13:20 12:10 2:20 10:08 12:04 11:14 1:04 9:12
Cycle 5 9:16 8:06 11:16 6:04 8:20 7:10 10:20 5:08 7:04 6:14 9:04 4:12
Cycle 6 4:16 3:06 6:16 1:04 3:20 2:10 5:20 13:08 2:04 1:14 4:04 12:12
Cycle 7 12:16 11:06 1:16 9:04 11:20 10:10 13:20 8:08 10:04 9:14 12:04 7:12
Cycle 8 7:16 6:06 9:16 4:04 6:20 5:10 8:20 3:08 5:04 4:14 7:04 2:12
Cycle 9 2:16 1:06 4:16 12:04 1:20 13:10 3:20 11:08 13:04 12:14 2:04 10:12
Cycle 10 10:16 9:06 12:16 7:04 9:20 8:10 11:20 6:08 8:04 7:14 10:04 5:12
Cycle 11 5:16 4:06 7:16 2:04 4:20 3:10 6:20 1:08 3:04 2:14 5:04 13:12
Cycle 12 13:16 12:06 2:16 10:04 12:20 11:10 1:20 9:08 11:04 10:14 13:04 8:12
Cycle 13 8:16 7:06 10:16 5:04 7:20 6:10 9:20 4:08 6:04 5:14 8:04 3:12
 --          --          --        
App 4-5 Di E Re W Di W Re E Di E Re W Di W Re E
Cycle 1 13:08 12:18 2:08 10:16 12:12 11:02 1:12 9:20          
Cycle 2 8:08 7:18 10:08 5:16 7:12 6:02 9:12 4:20          
Cycle 3 3:08 2:18 5:08 13:16 2:12 1:02 4:12 12:20          
Cycle 4 11:08 10:18 13:08 8:16 10:12 9:02 12:12 7:20          
Cycle 5 6:08 5:18 8:08 3:16 5:12 4:02 7:12 2:20          
Cycle 6 1:08 13:18 3:08 11:16 13:12 12:02 2:12 10:20          
Cycle 7 9:08 8:18 11:08 6:16 8:12 7:02 10:12 5:20          
Cycle 8 4:08 3:18 6:08 1:16 3:12 2:02 5:12 13:20          
Cycle 9 12:08 11:18 1:08 9:16 11:12 10:02 13:12 8:20          
Cycle 10 7:08 6:18 9:08 4:16 6:12 5:02 8:12 3:20          
Cycle 11 2:08 1:18 4:08 12:16 1:12 13:02 3:12 11:20          
Cycle 12 10:08 9:18 12:08 7:16 9:12 8:02 11:12 6:20          
Cycle 13 5:08 4:18 7:08 2:16 4:12 3:02 6:12 1:20          

Explanation

Each Venus Apparition consists of 4 columns in a row, with two numbers per column. The first number is the day count in the 1-13 day count; the second number represents the day name (see the table, "Key to Day Names." Thus, the upper left hand pair of numbers, 3:16 (boldfaced in the table; Below, I call it "GO," the start of the table), is 3 Cib; the lower right-hand pair, 1:20, is 1 Ahau.

1 Imix 11 Chuen
2 Ik 12 Eb
3 Akbal 13 Ben
4 Kan 14 Ix
5 Chicchan 15 Men
6 Cimi 16 Cib
7 Manik 17 Caban
8 Lamat 18 Edznab
9 Muluc 19 Cauac
10 Oc 20 Ahau

To use the table, start at the upper left with a disappearance of Venus in the East on day 3:16 (3 Cib) in the column marked "Di E." Venus had been a morning star. Venus reappears as an evening star on day 2:06 (2 Cimi) immediately to the right in the table, in column "Re W", and disappears on day 5:16 (5 Cib) shown to the right of this, in column "Di W". Finally it reappears as an evening star on day 13:04 (13 Kan) in column "Re E". Continuing to the right in this way, one next accounts for apparitions 2, 3, and in the lower half of the table, apparitions 4 and 5 of a cycle. When Cycle 1 is completed on day 9:20 (9 Ahau), go to Cycle 2 in the table and continue across the table in the same way. Then Cycles 3, 4, etc., through Cycle 13 are followed in the same fashion.

The error of the table at each apparition is 584-583.92=0.08 days, or 0.4 days per cycle of five apparitions (8 years). Since there are 13 cycles, after one complete trip through the table the error would be 13 x 0.4 = 5.2 days; the interval is too long. Therefore the Maya adopted a "recalibration" strategy to get around the problem. For example, upon ending the 61st apparition of the series (Apparition 1 of Cycle 13) on day 5:4 (boldfaced in the table), instead of looking for the disappearance of Venus on day 7:20 as expected, they would skip apparitions 62-65 and instead go back to the start of the table and look for Venus to reappear on Day 3:16, 4 days earlier in the Sacred Round. Thus, the error would be only 1 day instead of 5. But that meant starting again at "GO", (table top left). Similarly, they could stop at the end of apparition 57 (Apparition 2 of Cycle 12) on day 9:8 (boldfaced in the table), and instead of looking for Venus to disappear on day 11:4, go to "GO", and look for it to disappear 8 days earlier, on 3:16. This would be 4 days too early. By applying the first of these rules 4 times and the second once, the error in 4 x 61 + 57 = 301 apparitions (5 centuries) is only 0.08 days. (See Anthony Aveni, Empires of Time, pp. 229-230, for more information).


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