## Thursday, October 27, 2016

### The Struve Geodetic Arc produced the first accurate measurements of the Earth's size

Determining the size of the Earth is one of the most difficult problems for natural philosophers since ancient times. In the 2nd century BC, the Greek astronomer and mathematician named Eratosthenes began developing methods of measurement to calculate the meridian arc and compares it with the angle of the Earth's center.
 The northernmost station of the Struve Geodetic Arc is located in Fuglenes, Norway. (Picture from: http://adf.ly/1f4f32)
This method last up to two thousand years even though the accuracy of measurement is very low, ie approximately one percent. Eratosthenes calculates the arc length by measuring the time it takes for people to cross the desert and the angle by measuring the difference between the altitude of the Sun with latitudes.
 A Struve Geodetic Arc station in Hogland, Russia. (Picture from: http://adf.ly/1f4fRq)
 Map of the Struve Geodetic Arc where red points identify the  World Heritage Sites. (Picture from: http://adf.ly/1f4fRq)
In the 16th century, discovered a new measurement technique called triangulation. This method uses the arcs within the short to measure accurately, while the distance can be determined using a triangular link chain.

Triangulation allows the astronomers and cartographers to accurately measure the distance that stretch hundreds and thousands of kilometers. During the 18th century, many bows are built across Europe, but the longest is the Struve Geodetic Arc.

The Arc that stretches along 2,820 kilometers has allowed the most accurate Earth's measurements of the history. Yes, the man behind this arcs was a Russian-born German scientist named Friedrich Georg Wilhelm von Struve who conducted in-depth survey during 1816 up to 1855.

And the Struve Geodetic Arc consists of 258 triangles connecting 259 triangulation points, snaking from the northern coast of Norway to the southern coast of Ukraine. Currently, hundreds of points are located in 10 different countries namely Norway, Sweden, Finland, Russia, Estonia, Latvia, Lithuania, Belarus, Ukraine and Moldavia.
 A Struve Geodetic Arc station in Lithuania. (Picture from: http://adf.ly/1f4fRq)
As quoted of the Amusing Planet, the measuring stations or points marked in various ways, such as stone monument, memorial, rock drilled, until the sign of the cross on the rock surface. Of the overall 259 measurement points, 34 of which were recorded collectively in the list of UNESCO's World Heritage Sites. ***
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