The smaller numbers on the lunar table might also relate to the planets, notes Susan Milbrath, curator of Latin American art and archaeology at the Florida Museum of Natural History. That table ends with the number 4,784, which is nearly equal to the days elapsed in 12 synodic periods of Jupiter. "I think they were actually looking at the relationship of the lunar cycle to Jupiter, which is really intriguing," Milbrath says.
The researchers say that they are still peeling back the layers of meaning in the new find. "We're currently expanding the study of the possible astronomical implications of the Xultun inscriptions, and I think it is entirely possible that the Jovian period might have been involved as one of the periods of commensuration," says study co-author Anthony Aveni, a professor of astronomy, anthropology and Native American studies at Colgate. "There isn't much more we can say at this time, as there are no other inscriptions at Xultun that might relate to Jupiter, at least as far as we know."
"What we’re looking at in a couple examples now are different types of astronomical tables similar to the type that we know in bark paper books," Saturno says. Those manuscripts, or codices, which survive from later centuries, include dates going back to the Classic period, the era of Maya history from approximately A.D. 200 to 900. So it is no great surprise that the Maya were keeping astronomical records so early—the evidence of those records simply did not survive colonization or centuries of exposure in a tropical climate. Somehow the Xultun paintings and tables escaped destruction from weathering—and avoided drawing the attention of looters.
"These are our first records that surely show astronomical tables in the Classic period, which is a major discovery, I think," Milbrath says. "It's just an amazing find—it really is."