December 17 1790 – The Aztec Calendar Stone is Found in Mexico City

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*Image Credit: Wikimedia Commons In the midst of a massive project to strengthen the foundation of the Mexico City Cathedral, excavation came to a screeching halt on December 17, 1790. Underneath the Zocalo, the large central square of the Mexican capital, a huge circular stone carved with intricate symbols was discovered — the Aztec calendar stone. Three feet thick and twelve feet in diameter, the 25-ton rock was removed from its original perch when the Spanish conquered Mexico in 1521. Shortly after Hernan Cortes and his men captured Tenochtitlan and renamed it Mexico City, the Europeans went about destroying Aztec monuments in a bid to instill a new society built on the religion and customs of Spain. Temples were torn down and the massive Sun Stone, as the calendar is known, was hidden under the new streets laid down by the conquistadors. Upon being discovered on December 17, 1790, officials with the Catholic Church ordered it worked into the structure of the western tower, perhaps hoping to symbolically demonstrate once again the religion’s dominance over the pagan beliefs that preceded it. With expert care, architects and construction teams ensured it fit as well as possible with the existing building. More than a century later, long after Spain relinquished control of the New World and Mexico in particular, details about the young nation’s ancient history became a popular topic for study. In 1885, as the Aztec culture transformed into a revered feature of the Mexican identity, General Porfirio Diaz insisted the calendar be moved to the Museum of Archaeology and History. Believed at first to be a native take on the typical calendar, anthropologists have revised original theories to give the Sun Stone a special ritual significance. The Aztecs, unlike their European counterparts using the Julian calendar or its later Gregorian update, kept track of time with separate cycles for agriculture and religious purposes. These two systems overlapped once every 18,980 days — 52 years — creating a unique opportunity to engage the people in sustaining the sun for generations to come. In order to symbolically restart the sun’s burning core, priests would cut open the chest of a chosen victim and light a fire in the gaping wound. Far more than just a means to mark the time between New Fire festivals, the Sun Stone is now regarded as the resting place for the sacrifice. Calculating a 365-day year, with the addition of the 12-day-long ritual to breathe fresh life into the sun when the calendars matched up every five decades, the Aztecs had determined the Earth’s orbit lasted 365.2420 days. This number is slightly closer to the true value (365.2422) than the 365.2425 figured by the Gregorian version in 1582. Also On This Day: 1538 – Pope Paul III excommunicates King Henry VIII of England from the Roman Catholic Church 1777 – France formally recognizes the United States of America 1938 – Otto Hahn discovers nuclear fission — the splitting of atoms — at a lab in Berlin, launching the Atomic Age 1957 – The United States fires its first intercontinental ballistic missile 2010 – Tunisian street vendor Mohamad Bouazizi lights himself on fire in protest, starting the Tunisian Revolution that led to the Arab Spring of 2011