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Engineering and Technology Colloquia Series

Drawing the Map of the New World: Lunar Eclipses and Longitude in the 16th century Spanish Empire

Presented by: Maria Portuonodo (Johns Hopkins University)
Category: Engineering Colloquia   Duration: 1 hour and 30 minutes   Broadcast date: April 05, 2011
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How to map a New World? Not since the days of Ptolemy had geographers been faced with such a monumental task. The task was especially important to the Spanish Empire. For most of the sixteenth century its cosmographers led efforts to map the newly-discovered lands of the American continent and beyond. Longitude coordinates proved particularly troublesome in this era before accurate timepieces. In 1577, the Council of Indies initiated a project to determine the longitude of all of Spain’s overseas territories—from Iberia to the Philippines—by using a series of lunar eclipse that took place from 1577 until 1588. The objective was for novice observers to follow a simple set of instructions, record the lunar eclipse and send the observations to Spain. Back in Spain, cosmographers would complete the necessary mathematical computations and determine the respondents’ longitude. This talk will discuss the practices and instruments used, a few of the existing observations, and explain the cartographic outcome of the project.