## The Dresden Codex Mars Table

In 1924, Robert Willson identified the middle sections of pages 43-45 of the Dresden codex as a table of the motions of the planet Mars. The table deals with multiples of 780 days, whereas the mean synodic period of Mars is 779.93651 days. However, because 780 days is a triple multiple of the basic 260-day tzolkin or tonalpohualli of Mesoamerica, many scholars have supposed this to be a simple coincidence. Eric Thompson, in particular, argued repeatedly that the subdivisions of the table were too small and too numerous to have any purpose in connection with planetary movements. As in other cases, he made no attempt to consider the implications of the Ring Number (see §12.10), which introduced the table and which lies 352 days before the usual Maya era base. Willson (1924, pp. 24-25 et passim) has pointed out that the interval from Mars's conjunction with the Sun to its first stationary point was about 352 days, followed by an interval of 76 days and then by a second interval of 352 days (see §§2.4.3, 7.1.4.4 for details of planetary configurations). The combined interval, 780 days, is the synodic period, with Mars returning to conjunction at the end of the interval. Because the table interval is 78 days, arranged 19-19-19-21, the Mars arrangement would have to be considered 351-78-351 days for the table to be a viable representation of Mars's motion. The nonuniform motion of both Earth and Mars (especially, the latter; see §2.4) due to their eccentric orbits will permit such variations to occur from year to year, as we note below. Willson's analysis would suggest that the Ring Number 3 Lamat was at the second stationary point, and that the era base 4 Ahau 8 Cumku, was at or very near Mars's conjunction with the Sun. Neither Willson nor Thompson seemed to be aware, however, that Mars's actual motions are seldom close to its mean interval. Tabular almanac data reveal that deviations of successive Mars conjunctions from the mean are frequently as much as ±20 days. This may provide an explanation for the short intervals in the 3 Lamat table, which so distressed Thompson.

In 1980, Kelley pointed out that his postulated 12 Lamat 1 Pop base for calculating the calendar names of the gods would put the name of the Mars god in the month Zip and that the deity of Zip was precisely the "sky peccary" who had been identified by Willson as Mars because of his appearance in the pages of the Dresden codex. More recently, V. and H. Bricker (1986) presented further arguments about the relationship of the Mars dates in the table with real-time events, using the 584,283 (the later Thompson) correlation. Although Kelley rejects this correlation, the arguments retain some validity when rephrased in more structural terms. On the basis of the Brickers' work, Juste-son (1983, p. 25) has accepted the 3 Lamat table as a Mars table.

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