Astronomy and Calendar of the Incas

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2016 Ticket Machu PicchuThe Incas had great knowledge of astral space, a product of detailed observation; they knew the Milky Way, which they called "MAYU" which translated from Quechua means "heavenly river"; likewise they differ in their constellations two types: the first, consisting of the most outstanding stars, and the second by cosmic clouds.

Constellations identified by the Incas

Among the major constellations identified by the Incas, they are: Chakana – South cross, Qolqa – Pléyades, Atoq – Fox, Amaru – Snake, Kuntur – Condor, Llut’u – Partridge, Mallki – The tree of life, Katachillay – The llama, Hamp’ato – Toad, etc.

calendario inca machu picchu
Festival of the Sun or Inti Raymi, celebrated in Sacsayhuaman, Cusco

Weather forecast at the time of the Incas

The Incas also understood the influence of the moon and the stars, in the way people behave plants and animals. They were able to identify the lunar phases, which could predict the times of rain and drought, astronomical observation, also it help them to identify the suitable time for planting and harvesting, remember that the Incas considered the Sun, Moon and Stars, divine beings.

The Incas not sow neither harvested never in new moon, on the contrary they did it on full moon. When they made wooden buildings, were built during the full moon phase, to avoid apolillamiento. They also observe the moon’s position for success in their battles.


Eclipses at the time of the Incas

Moles or sun eclipses were regarded as anger or distress of these deities; in order to appease their anger or prevent that turn off completely, the Inca people performed llama sacrifices with fasting, praise and tears. The passage of a comet, was a negative omen for the empire, either death, natural disasters or wars.


Inca Calendar

This observation of the cosmos, made that the empire conceived a solar year compound of 12 months, and each of these, consisting of 30 days, divided into 3 weeks of 10 days each. The last day was considered a fair or market day (qhatu), where you could exchange goods (barter).

The beginning of the Inca year, was at different dates, depending on the regions of the empire; in the city of Cusco (the capital of Tahuantinsuyo), the year began in the month of August, a date that coincided with the beginning of agricultural activity.

According to scholars of Inca civilization, the calendar used by the ancient Peruvians was as follows:

  • Raymi (December) – La gran pascua del Sol, Huarachicuy.
  • Camay (January) – Penitence and fasting of the Incas.
  • Jatunpucuy (February) – Month of flowers in which sacrifices with huge amounts of gold and silver were made.
  • Pachapucuy (March) – Month of rain, animals were sacrificed.
  • Arihuaquis, (April) – Maturation of maize and potatoes (main food of the Inca people).
  • Jatuncusqui (May) – Harvest month.
  • Aucaycusqui (June) – Feast in honor of the Sun god (Inti Raymi), coincides with the winter solstice.
  • Chaguahuarquis (July) – Month in which he carried out the distribution of land, and preparation for planting.
  • Yapaquis (August) – Month planting.
  • Coyarraimi (September) – Feast in honor of the Coya (queen), and to expel evil spirits and disease.
  • Humarraimi (October) – Period for the invocation of the rain.
  • Ayamarca (November) – Time to worship the dead.


Timetable Inca, Division of day

The day was divided as follows: dawn, full morning, midday, sunset, dusk, the night and midnight.


The seasons

The Incas knew the solstices and equinoxes to perfection, dates were celebrated with great rituals of adoration and worship. Therefore the Incas determined two seasons:

  • The dry season – Ch’akiy.
  • The rainy season – Poqoy.


Astronomical Observatories

Usually, the observatories are located in their temples, but could also be found observatories on the tops of some mountains like Huayna Picchu. It is known that the "Incas astronomers", lived close to the tops of the mountains, which were dedicated full time to observing the behavior of the stars, also they used the reflection of water (water mirrors), and the projection of light and shadow, in sundials as the Intihuatana, being able to determine very accurately, the dates of the solstices and equinoxes.



The Incas had many holidays, which were also considered as days of rest; which usually they were linked to agriculture. Some of these celebrations were held on fixed days, but others were determined by the highest authority of the empire, the Inca.

The celebrations were popular ceremonies with music and song, which could last from three to seven days. Some of the Inca festivals still celebrated today in the city of Cusco, one of the most famous and popular, is the Inti Raymi – Sun Festival, which coincides with the winter solstice (June 21) and the celebrations for the anniversary of the city of Cusco. Another of the Inca festivals still celebrated in some provinces of the department of Cusco, is the Qhapaq Raymi, which coincides with the summer solstice (December 22).



By Ticket Machu Picchu – Last Update, 16-03-2016


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