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WonderGeodesy fact

The Struve Geodetic Arc is a 2,820-kilometre chain of survey points running from Norway to the Black Sea. Between 1816 and 1855, surveyors used it to measure a long north-south line across the globe and work out the size and shape of the Earth.

Struve Geodetic Arc

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The story behind the card

The survey was led by Friedrich Georg Wilhelm Struve, a German-born astronomer who directed the observatory at Dorpat, now Tartu in Estonia, where the chain's first point still stands. It used triangulation: surveyors measured a base line very precisely, then worked out every further distance by measuring the angles between distant hilltops and towers. The finished chain has 258 main triangles and 265 station points, from Hammerfest in Norway to a point near the Black Sea in Ukraine. When it was built it crossed only three states, Norway, Sweden and the Russian Empire; today it crosses ten. The results, published in 1858, put the Earth's flattening at the poles at about 1 part in 294, close to today's figure of 1 in 298. In 2005 UNESCO listed 34 of the station points as a World Heritage Site.

Türkçe oku
Struve Jeodezi Arkı, Norveç'ten Karadeniz'e uzanan 2.820 kilometrelik bir ölçüm noktaları zinciridir. 1816 ile 1855 arasında bu zincir boyunca kuzeyden güneye uzun bir hat ölçüldü ve Dünya'nın büyüklüğü ile biçimi o güne dek görülmemiş bir doğrulukla hesaplandı.

Ölçümü, Alman asıllı gökbilimci Friedrich Georg Wilhelm Struve yönetti. Struve, bugün Estonya'da bulunan Tartu'daki (o zamanki adıyla Dorpat) gözlemevinin müdürüydü; zincirin ilk noktası hâlâ bu gözlemevinde durur. Yöntemin adı nirengidir: önce bir taban çizgisi çok titizlikle ölçülür, sonra uzaktaki tepeler ve kuleler arasındaki açılar ölçülerek öteki bütün uzaklıklar hesaplanır. Zincir 258 ana üçgenden ve 265 ölçüm noktasından oluşur; Norveç'teki Hammerfest'ten Ukrayna'da Karadeniz'e yakın bir noktaya kadar iner. Kurulduğunda yalnızca üç devletten geçiyordu: Norveç, İsveç ve Rus İmparatorluğu. Bugün on ülkeden geçer. 1858'de yayımlanan sonuçlara göre Dünya kutuplarda yaklaşık 294'te 1 oranında basıktır; bugün kabul edilen değer 298'de 1'dir. UNESCO, ölçüm noktalarından 34'ünü 2005'te Dünya Mirası listesine aldı.

Sources and further reading

Background reading: Struve Geodetic Arc
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