Encyclopedia of the Incas

calendar. The calendar regulated ritual activities in the city and around the
empire, and it was also important in the timing of the agricultural and herding
cycles and activities on which the imperial economy depended.
With the exception of Venus, there is little solid evidence in the chronicles that
Inca astronomers closely observed planetary motions. The Incas observed Venus
of the morning and the evening and both were referred to as chaska (shaggy
hair). Given the richness and complexity of Inca astronomical observations, it
remains a mystery as to why so little attention was apparently paid to the planets.
Perhaps evidence for additional planetary observations will be identified in
sources in the future.
There are rich sources of information on Inca observations of the stars and
constellations. Two factors affecting stellar observations must be taken into
account. First, the Inca Empire lay almost entirely within the southern
hemisphere (Cuzco, the capital, lies at a latitude of 13°30'S latitude). In fact, one
of our sources, the chronicler Garcilaso de la Vega, informs us that the Incas
were actually intent on carrying their conquests northward from Cuzco to the
place “where the sun sat most comfortably between its extremes.” The latter
would have defined the equinox, the point equidistant between the extremes of
the north and south solstice rise and set points. Because of the southern
hemisphere location of the empire, the Incas had a view of the stars in the
southern celestial hemisphere, including the south celestial pole, although they
would not have been familiar with the north celestial pole, or many of the stars
and constellations of far northern latitudes in the northern celestial hemisphere.
It is important to note that the south celestial pole is not marked by a pole star,
such as the star Polaris, which stands at the north celestial pole. It is perhaps
partially because of the absence of a persistent view to a fixed pole star that the
Incas appear to have had little interest in the cardinal directions.
The second point to take into account concerning Inca stellar observations is
that the identities that they assigned to the stars and constellations were ones that
were meaningful to them, in terms of their religious beliefs, mythological
traditions, economy, and so forth. That is, we should not expect, nor do we find,
that the Incas recognized the constellations that are familiar to northern
hemisphere stargazers, which mostly come down to modern Euro–North
American populations from Greek and Roman traditions (e.g., Gemini,
Sagittarius, Cancer, etc.). Instead, the Inca projected into the heavens the
identities of the animals, birds, and other objects of nature and culture that made
up their own world. Thus, for instance, they recognized in the cluster of stars