Th e Latin literary tradition also includes astronomical
material, with Roman writers adapting it to their own cul-
tural and social contexts. Th e poet Virgil (70–19 b.c.e.) bases
parts of his Georgics on the Greek agricultural poem Work s
and Days of Hesiod (late eighth century b.c.e.), a major source
for early Greek observational astronomy. Political elements
appear in the Georgics as well. For example, Virgil suggests
that the origin of the constellation Libra derives from cosmic
support for the emperor Augustus. Ovid, too, incorporates
into his epic Metamorphoses elements from the account of the
beginnings of the universe in Hesiod’s Th eogony. A number
of tales in Ovid’s works also recount instances of cataster-
ism, the transformation of a mortal into a star, constellation,
or other celestial object. Th is concept was not restricted to
myths, for at the very end of the Metamorphoses, Ovid de-
scribes the ascent of Julius Caesar’s spirit as a comet, known
as the Sidus Iulium (“Julian Star”). Ovid also wrote in praise
of astronomers in his Fasti (Festivals), a poem explaining the
myths associated with the traditional Roman calendar.
Popular handbooks of astronomy appear during the
Roman period. While many were in Greek, such as that of
Geminus (ca. 110–40 b.c.e.), the De astronomia (Concern-
ing Astronomy) of Hyginus (early fi rst century c.e.) was an
important Latin work. In addition to outlining the basics of
astronomy, the author retells from Greek sources the myths
related to the constellations. Vitruvius (late fi rst century
b.c.e.) includes an account of the heavens in his work on ar-
chitecture. Another important fi gure was Pliny the Elder (24–
79 c.e.), whose second book of the Naturalis historia (Natural
History), preserved for later ages valuable information about
the scientifi c astronomy of the day.
THE AMERICAS
BY J. J. GEORGE
Most ancient American cultures paid attention to what was
happening in the sky. Th e periodic cycles of the sun, moon,
stars, and planets, being reliable and predictable, allowed
for the development of the calendar. Broadly speaking, as-
tronomy was one area that contributed to a greater Meso-
american cosmology, and subsequent uses helped defi ne and
order such areas as agriculture, site orientation, astrology,
myth, shamanism, divination, and even warfare. Our best
astronomical data come from successful early agricultural
cultures in Mesoamerica—the Olmec of the Gulf Coast of
Mexico (1500–400 b.c.e.), the Zapotec of the Valley of Oaxa-
ca at Monte Albán (600 b.c.e.–900 c.e.), and the inhabitants
just outside the Basin of Mexico at Teotihuacán (1 b.c.e.–650
c.e.). Th e Classic Period Maya (200–900 c.e.), building upon
earlier Mesoamerican thought, established the clearest as-
tronomical record. Astronomy in the ancient period focused
on horizon and zenith events of the rising and setting sun,
moon, planet Venus, and star cluster Pleiades and on the sa-
cred four cardinal directions.
Th e beginnings of the Mesoamerican calendar signifi ed
the fi rst concrete astronomical achievement. A carved stela,
or upright stone, from La Mojarra on Mexico’s Gulf Coast
(150 c.e.), exhibits in hieroglyphic form the beginnings of a
solar 365-day calendar. When used in tandem with a unique
260-day sacred calendar (called the Tzolkin), like a system of
interlocking cogwheels, this stela established everything in
the Mesoamerican world, from agricultural rites to ritual and
religious ceremonies to feasts and the inauguration of New
Year. Th is stela also records a hieroglyph for Venus as well as
a date that correlates with a visible solar eclipse. Th e Mayans
later developed an extraordinarily accurate Venus table as
well as an eclipse table that accurately predicted the occur-
rence of those celestial events.
Mesoamerican site orientation, the layout of a particular
ritual site or city across the landscape, oft en had astronomical
signifi cance. For example, a structure referred to as Build-
ing J at Monte Albán strongly suggests an astronomical rela-
tionship. Building J is unique in that it is roughly pentagonal
(with a “pointer” side and a stairway side) and set consider-
ably askew (nearly 45 degrees) from the general site orien-
tation. Recent research suggests that Building J aligns with
another building (Building P) to form a sightline that extends
to the horizon point where the rising star Capella announces
the solar zenith passage.
Similarly, Building J aligns with a neighboring site,
Caballito Blanco, which has a similar skewed building. A
straight line between the two coincides with the sunset posi-
tion on the horizon on the day of the solar zenith passage,
when at local noon the sun is directly overhead and casts no
shadow of perfectly vertical structures. In the opposite direc-
tion the line marks the sunrise azimuth on the morning aft er
the antizenith (nadir) passage, when the sun is directly below
at local midnight. It has been suggested that Building J was a
calendar temple, a structure that embodied numerology and
astronomy and permitted Mesoamericans to create their in-
terlocking calendars.
By 550 c.e. Teotihuacán, northeast of modern-day Mexico
City, was the sixth-largest city on the planet, with an estimat-
ed population between 125,000 and 250,000. Th e Aztecs later
called Teotihuacán the place where time began and centered
their origin myths there. Astronomical alignments were used
at Teotihuacán for overall site orientation and to orient more
specifi c dates related to agriculture and the sacred calendar.
Th e overall orientation of its grid pattern falls within what
is oft en referred to as the 17-degree family of orientations, a
group of orientations widely distributed throughout Meso-
american sites with axes typically 15 to 18 degrees clockwise
from the cardinal directions.
Punctuating the grid of Teotihuacán is a large, fl at-topped
pyramid called the Pyramid of the Sun (a second pyramid on
the site is called the Pyramid of the Moon; both names are at-
tributed to the later Aztec) and a ceremonial structure called
the Ciudadela, both skewed approximately 15.5 degrees andastronomy: The Americas 133