Dorpat Observatory

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The Astronomical Observatory (Tähetorn) of the University of Tartu (Dorpat until 1919) has played an important role in the history of European astronomy. Some 120,000 stars have been registered from here.

The cruciform Observatory was built in 1810. It was designed by Architect Johann Wilhelm Krause (1757-1828) in tandem with the Rector and Professors of Astronomy and Mathematics using the observatories of Gotha, Göttingeni and Uppsala as models. It was here that Freiderich Georg von Struve (1793-1864) came to work in 1813- 39. Struve had come to Tartu from his native Altona, Germany, to study philology but soon found his true vocation. He lived in the house that still stands next to the Observatory and that was connected to it by a private corridor specially constructed for his convenience by the university Board. In 1820 Struve became the Director of the Observatory. Rector Ewers also made him Night Rector on the premise that since Professor Struve was up at night studying the stars, he could also keep an eye on students who should be in bed. Moreover, Struve was made a voluntary fireman who would sound the alarm if fire broke out.

In 1824 Struve commissioned a telescope with a lens that was, at the time, the largest in the world. The rotating round tower was built to house this state-of-the-art technology. The refractors allowed Struve to expore the heavens in some detail and among his many achievements was the first measurement of the distance of the star Vega from earth. A model of Struve’s telescope can be seen in the Old Observatory Museum on the ground floor. Booked visits only - phone +372 737 6932 or e-mail: ahhaa@ahhaa.ee

Struve was also a geoesist – one who determines shapes and distances using trigonometry and geometry – and cartographers from the Army and Navy were sent to him to study. In 1839 Struve moved to St Petersburg where he built the biggest and most up-to-date observatory in the Tzarist empire.

Struve’s most important achievement was the construction of the ‘Struve Geodetic Arc’. The Arc is a chain of survey triangulations stretching from Hammerfest in Norway to the Black Sea, through ten countries and over 2,820km. These are the points from a survey carried out between 1816 and 1855 by Astronomer Struve that were used to make the first accurate measuring of a long segment of a meridian. This helped establish the exact size and shape of the planet and marked an important step in the development of earth sciences and topographic mapping. It was an extraordinary example of scientific collaboration among scientists from different countries, and of collaboration between monarchs for a scientific cause. The original arc consisted of 258 main triangles with 265 main station points.

In 1969 the Soviet authorities erected an hour glass-shape dolomite memorial to Struve on the green outside the Observatory. It marks the exact coordinates of the meridian at Tartu Observatory east of Greenwich ; longitude 1t 46m 53s.18 i.e. 26° 43' 17.7;latitude 58° 22' 47'. A joint application for inclusion of the Struve Geodetic Arc into the UNESCO World Heritage list made by Finland on behalf of Finland, Norway, Sweden, Russia, Estonia, Latvia, Lithuania, Byelorussia, the Ukraine, and Moldova was approved in 2005. The listed site includes 34 of the original station points consisting of a variety of marks, i.e. a drilled hole in rock, an iron cross, cairns, or man-made obelisks.

Other notable astronomers who have worked at the Observatory include Johann Heinrich Mädler (1794-1874) who was active in the field of stellar dynamics and cosmology. He compiled a catalogue of binary stars, an atlas of the moon and a popular handbook of astronomy. In the 20c Ernst Julius Öpik (1893-1985) worked here from 1921-1944 (bar four years in Harvard) . He fled in 1944 and worked in the UK for most of the rest of his life.

Until 1914 the Observatory remained among the best in Europe. The last observation was made from the Observatory in 1985 but its useful life is far from over. Since 1997 it has been used by the AHHAA project. The project started its activities with a laser show from the Observatory in September 1997 and hasn’t looked back since. The aim of AHHAA is to introduce science to ordinary people using interactive, entertaining methods. Major exhibitions have included Aha, Insects! (in co-operation with the Natural History Museum in London), Aha, Time!. Aha, Human!, Aha, Light!, Aha, Senses!, Aha, Laboratory! The Mystery of Ancient Egypt (in cooperation with the Finnish Science Centre), Sweet Europe and an exhibition of holograms and a concert to celebrate the Earth’s closest position to the Sun. Since 1997, more than 300.000 visitors have visited AHHAA events - a very impressive record in a nation of only 1.5 million people. For information in English go to http://www.ahhaa.ee/index.php?page=31&agrupp=&op=&keel=eng. A new AHHAA centre is planned in 2006.