Struve Geodetic Arc . It indicates the first exact measurement of a long segment of the Earth’s meridian, it is an extraordinary example of scientific collaboration between sages from different countries, as well as an example of cooperation between various European monarchs for scientific progress.
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- 1 Description
- 2 Expeditions
- 3 Results
- 4 Countries that cross the Struve Arch
- 5 Importance
- 6 Sources
Of the works that make up the UNESCO World Heritage , one of the most curious is the Struve Arch. It consists of a chain of geodetic points that extend from Hammerfest ( Norway ) to the north, to the Black Sea in the south, through ten countries and over some 2,820 km.
Determining the dimensions of our planet was the great scientific challenge of the 18th and 19th centuries. For this, meridian arcs were calculated, lines perfectly oriented in the north-south direction. Among the theorists there was no consensus, Jacques Cassini imagined that the Earth had an ellipsoid shape, with the polar radius greater than the equatorial, that is, as a rugby ball with the longest side vertically. For his part, Huygens thought that the Earth was flattened by the poles. Newton’s theory of gravitationit agreed with Huygens’ idea and predicted that our planet was an oblate spheroid. Astronomers’ expeditions to different parts of the planet sought to compare the dimensions of a meridian arc measured near the North Pole with those of another arc measured near the Equator .
The great powers organized expeditions to measure the meridian arc, France sent Pierre Bouguer and Charles Marie de La Condamine to South America with the idea that from the peaks of the Andes it would be easy to take reference points to make the triangulations. In reality, the Andean mountains used to be covered in mist and scientists had to wait weeks for their measurements to be made. Since Ecuador was Spanish territory, King Louis XV asked his cousin, King Felipe V, for permission., to go into the Andes. The king agreed in exchange for the expedition having Spanish scientists. The chosen ones were Antonio de Ulloa and Jorge Juan and Santacilia.
The expedition has gone down in the history of Science as one of the harshest that any scientist has ever faced, nine years of calamities and fighting the elements. The expedition left in May 1735 for Cartagena de Indias and after disagreements between La Condamine and Bouguer they separated into three groups on the way through the jungle . Meanwhile, another French team led by Pierre Maupertuis and the Swedish physicist Ander Celsius (the inventor of the famous thermometric scale) had moved to Laplandand he managed to show that the degree is greater near the poles, as Newton had predicted. It was clear that our planet was far from being a perfect sphere.
To refine these measurements, between 1816 and 1855 the German astronomer Friedrich Georg Wilhelm von Struve carried out a set of triangulations that spans ten countries, over 2,820 km, from Hammerfest (Norway) to the Black Sea . The Struve arc includes 265 vertices. 34 of the original fixed points are included in the UNESCO World Heritage Site , the vertices are marked differently: perforations in rocks, iron crosses, burial mounds and obelisks, which represent the first exact measurement of a sufficiently long segment of the terrestrial meridian. Among them, the Tartu observatory .