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laid out in a neat grid along a trade route.
There, a battered stone stela excavated
in 1989 bears a Long Count date frag-
ment that may refer to an unknown event
around 300 B.C.E.
Christa Schieber de Lavarreda, the site’s
archaeological director, points to a flat
stone, considered an altar, found face-up
just a few feet away, which archaeologists
think was installed at the same time as
the stela. Its surface is indented with deli-
cate carvings of two bare feet, toe pads in-
cluded, as if a person stood there and sank
in a few centimeters. “Very ergonomic,” she
jokes. If someone stood in those prints, she
says, they would have faced where the Sun
rose over the horizon on the winter sol-
stice, the year’s shortest day.
For Zunil daykeepers and other Indig-
enous groups, sites like this are sacred places
where ancient knowledge comes alive; their
right to conduct ceremonies here is codified
in Guatemalan law.
The surrounding ancient city contains
more clues to ancient astronomical aware-
ness. The plaza containing the date inscrip-
tion, for example, belongs to a common style
that Maya city planners apparently followed
for more than 1000 years. The eastern side
of the plaza features a low, horizontal plat-
form running roughly north to south, with a
higher structure in the middle. On the west-
ern side is a pyramid topped with a temple or
the eroded nub of one (see graphic, below).
Beginning in the 1920s, archaeologists be-
gan to clamber up these pyramids in the early
mornings and look east, toward the rising
Sun over the platform, suspecting the com-
plexes might mark particular solar positions.
A stream of recent data supports the idea,
Šprajc says. In 2021, he analyzed 71 such pla-
zas scattered through Mexico, Guatemala,
and Belize, measured either with surveying
equipment on his own jungle forays or with
lidar, a laser technology sensitive to the faint
footprints of ruins now buried under forest
and earth. In the most widespread shared
orientation, someone standing on the central
pyramids would see the morning Sun crest
over the middle structure of the oppositeplatform twice a year: 12 February and 30 Oc-
tober, with a suggestive 260 days in between.
Perhaps, Šprajc argued in PLOS ONE, these
specific sunrises could have been marked
with public gatherings or acted as a kickoff
for planting or harvesting festivals.
Ongoing research suggests designers of
e v e n o l d e r a r c h i t e c t u r e s h a r e d a s i m i l a r w o r l d -
view. In 2020, archaeologist Takeshi Inomata
of the University of Arizona used lidar data
to spot a vast, elevated rectangular platform,
with 20 subplatforms around its edges, that
stretched 1.4 kilometers in Tabasco, Mexico.
Reported in Nature, the structure dates backto between 1000 and 800 B.C.E., before direct
archaeological records of Maya writing and
calendar systems. At the big complex’s very
center, Inomata found the raised outlines of
the pyramid-and-platform “E-group” layout
thought to be a solar marker.
In a 2021 study in Nature Human Be-
haviour, Inomata used lidar to identify
478 smaller rectangular complexes of similar
age scattered across Veracruz and Tabasco;
many have similar orientations linked to
sunrises on specific dates. In unpublished
work with Šprajc and archaeoastronomer
Anthony Aveni of Colgate University, Inomata
is now reanalyzing the lidar maps to see
what sunrises people at those spaces might
have looked to, perhaps dates separated by
20-day multiples from the solar zenith pas-
sage, when the Sun passes directly overhead.
For later periods of Maya history, scholars
seeking astronomical evidence rely more on
inscriptions. Long after the Tabasco platform
was erected, during a monument-building
florescence spanning most of the first mil-
lennium C.E. called the Classic Period,
generations of Maya lavished attention on
calculating the dates of new and full Moons,
sorting out the challenging arithmetic of the
lunar cycle’s ungainly 29.53 days. At Copan in
modern-day Honduras and surrounding cit-
ies, early 20th century archaeologists found
engravings that record one “formula” for
tracking the Moon that is only off by about
30 seconds per month from the value mea-
sured today; at Palenque, in southern Mexico,
another version of the same formula is even
more accurate.
Some recent discoveries about this time
period focus on the astronomers themselves.
In 2012, archaeologists described a ninth
century wall mural in Xultún, Guatemala,
in which a group of uniformed scholars
meets with the city’s ruler. On nearby walls
and over the mural itself, scholars scribbled
the same kind of lunar calculations as in
Palenque; one even appears to have signed
their name underneath a block of arithme-
tic. A skeleton of a man wearing the uniform
depicted in the mural was later buried un-
der the floor of this apparent Moon-tracking
workshop; a woman with bookmaking tools
was also buried there.
Clues like the Xultún mural point to a net-
work of scholars serving in Classic Period
royal courts, says David Stuart, an epigrapher
at the University of Texas, Austin, involved
with the Xultún excavations. These specialists
tracked celestial events and ritual calendars,
communicating across cities and generating
what must have been reams of now-vanished
paper calculations. “The records we see imply
the existence of libraries of records of astro-
nomical patterns,” Stuart says, which rulers
likely used to pick out fortuitous future dates. CREDITS: (MAP K. FRANKLIN AND V. ALTOUNIAN/SCIENCE; (DA0 200
kmMEXICO BELIZEGUATEMALAHONDURASNICARAGUAEL SALVADORMérida
Chichén Itzá
UxmalPalenqueTak’alik Ab’aj CopanXultúnGuatemala CitySightlineModern cityMaya archaeological siteSelected “E-group” sitesMaya civilization E-group design
From the pyramid, viewers
looking east see the Sun rise above
the opposite platform.A Maya motif
For more than a millennium of early Maya history, major cities and dozens of
smaller communities alike featured an architectural layout that may have been
used to mark—and memorialize—the rising Sun on particular dates.