Struve Geodetic Arc

The Struve Geodetic Arc is a chain of survey triangulations stretching from Hammerfest in Norway to the Black Sea, through ten countries and over 2820 km, which yielded the first accurate measurement of a meridian arc.

The chain was established and used by the German-born Russian scientist Friedrich Georg Wilhelm von Struve in the years 1816 to 1855 to establish the exact size and shape of the earth. At that time, the chain passed merely through three countries: Norway, Sweden and the Russian Empire. The Arc's first point is located in Tartu Observatory in Estonia, where Struve conducted much of his research. Measurement of the triangulation chain comprises 258 main triangles and 265 geodetic vertices. The northernmost point is located near Hammerfest in Norway and the southernmost point near the Black Sea in Ukraine.

In 2005, the chain was inscribed on the World Heritage List, because of its importance in geodesy and its testimony to international scientific cooperation. The World Heritage site includes 34 commemorative plaques or built obelisks out of the original 265 main station points which are marked by drilled holes in rock, iron crosses, cairns, others. This inscription is located in ten countries, the second most of any UNESCO World Heritage after the Ancient and Primeval Beech Forests of the Carpathians and Other Regions of Europe.

The measurements of the 30° Meridian Arc in 1816–1852 as well the description of the geodesic, topographical, and map making works in the Balkans from the nineteenth century until the beginning of the twentieth century by Russian Czarist Army was described in Astronomy, geodesy and map- drawing in Moldova since the middle ages till the World War I.

Norway

 * Fuglenes in Hammerfest (70.67°N, 23.66333°W)
 * Raipas in Alta (69.93861°N, 23.36028°W)
 * Luvdiidcohkka in Kautokeino (69.66444°N, 23.60222°W)
 * Baelljasvarri in Kautokeino (69.02861°N, 23.30528°W)

Sweden

 * "Pajtas-vaara" (Tynnyrilaki) in Kiruna (68.255°N, 22.98306°W)
 * "Kerrojupukka" (Jupukka) in Pajala (67.27667°N, 23.24306°W)
 * Pullinki in Övertorneå (66.64639°N, 23.78194°W)
 * "Perra-vaara" (Perävaara) in Haparanda (66.01806°N, 23.9225°W)

Finland

 * Stuor-Oivi (currently Stuorrahanoaivi) in Enontekiö (68.6825°N, 22.74583°W)
 * Avasaksa (currently Aavasaksa) in Ylitornio (66.39778°N, 23.72528°W)
 * Torneå (currently Alatornio Church) in Tornio (65.83°N, 24.15722°W)
 * Puolakka (currently Oravivuori) in Korpilahti (61.92667°N, 25.53361°W)
 * Porlom II (currently Tornikallio) in Lapinjärvi (60.70472°N, 26.00333°W)
 * Svartvira (currently Mustaviiri) in Pyhtää (60.27639°N, 26.60333°W)

Russia

 * "Mäki-päälys" (Mäkipäällys) (Finland 1917/1920-1940) in Gogland (Suursaari)(60.07417°N, 26.96972°W)
 * "Hogland, Z" (Gogland, Tochka Z) in Gogland (60.08606°N, 26.96042°W)

Estonia

 * "Woibifer" (Võivere) in Väike-Maarja Parish (59.05778°N, 26.33778°W)
 * "Katko" (Simuna) in Väike-Maarja Parish (59.04833°N, 26.41417°W)
 * "Dorpat" (Tartu Old Observatory) in Tartu. (58.37879°N, 26.72017°W)

Latvia

 * "Sestu-Kalns" (Ziestu) in Ērgļu novads (56.84°N, 25.63667°W)
 * "Jacobstadt" in Jēkabpils (56.50139°N, 25.85667°W)

Lithuania

 * "Karischki" (Gireišiai) in Panemunėlis (55.9025°N, 25.43667°W)
 * "Meschkanzi" (Meškonys) in Nemenčinė (54.93083°N, 25.31667°W)
 * "Beresnäki" (Paliepiukai) in Nemėžis (54.63444°N, 25.42917°W)

Belarus

 * "Tupischki" (Tupishki) in Ashmyany district (54.29167°N, 26.04528°W)
 * "Lopati" (Lopaty) in Zelva district (53.56056°N, 24.86972°W)
 * "Ossownitza" (Ossovnitsa) in Ivanovo district (52.28944°N, 25.64944°W)
 * "Tchekutsk" (Chekutsk) in Ivanovo district (52.20778°N, 25.55639°W)
 * "Leskowitschi" (Leskovichi) in Ivanovo district (52.16083°N, 25.57139°W)

Moldova

 * "Rudi" near Rudi village, Soroca district (48.31889°N, 27.87667°W)

Ukraine

 * Katerynivka in Antonivka, Khmelnytskyi Oblast (49.56583°N, 26.75611°W)
 * Felshtyn in Hvardiiske, Khmelnytskyi Oblast (49.33°N, 26.68194°W)
 * Baranivka in Baranivka, Khmelnytskyi Oblast (49.14861°N, 26.99167°W)
 * Staro-Nekrasivka (Stara Nekrasivka) in Nekrasivka, Odesa Oblast (45.33264°N, 28.92778°W)

Historical
At publication in 1858, the flattening of the earth was estimated at one part in 294.26. The earth's equatorial radius was estimated at 6378360.7 meters.

In 2005, the work was repeated using satellite navigation. The new flattening estimate was one part in 298.257 222 101 and the equatorial radius was 6378136.8 m.

An earlier survey, in 1740, had given flattening at one part in 178 and an equatorial radius of 6396800 m.

Modern
Northernmost point: Hammerfest (Fuglenes): 70° 40' 11.23″ N

Southernmost point: Ismail (Staro-Nekrassowka): 45° 20' 02.94″ N

Difference in Geodetic Latitude: 25° 20' 08.29″

Distance in kilometres: 2,821.853 ± 0.012