Colonial Churches as Astronomical Instruments in San Cristóbal de las Casas: Informe Preliminár—Archivos de la Catedrál
There are many documented examples of meridian lines in Italian churches in the 14th and 15th centuries. Hilbron (1999) discusses how these lines and others were used to measure the date of the equinox, the sun's altitude on the day of the summer solstice, the earth's annual motion, its obliquity, and other topics of interest to astronomers. No published instances of these astronomical uses of churches have been found for in Latin America. We report here a new finding, that meridian lines were also constructed in the Americas, in 17th and 18th century churches in Chiapas, Mexico. They traced the principle aisle of the church. Incredibly, although the lines continue to provide a spectacular light show, their meaning has been lost. Even more astonishing is the finding that these 17th and 18th century churches were designed to produce these impressive light shows. Old World churches were retrofitted for Meridian lines by breaking holes in the roof or cutting them into stained glass installations. Four of the churches studied in San Cristóbal de las Casas, were designed from the ground up to cast equinoctial and solsticial beams of light.
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