BOOKLET - Tartu Old Observatory - The World Heritage Objects. The Struve Geodetic Arc.
Available in 6 languages - English, German, Russian, Finnish, Latvian and Estonian.
The Arc, stretching 2820 km through ten countries from the coast of the Arctic Ocean in Norway to the mouth of River Danube at the Black Sea, reminds about the international geodetic surveying works organized by the astronomer F. V. G. Struve in the beginning of the 19th century. They significantly influenced the course of development of science and helped establish the exact size and shape of the Earth.
The Struve Geodetic Arc is a chain of survey triangulations stretching from the Black Sea to Norway’ northern coast on the initiative of Friedrich Georg Wilhelm Struve (1793-1864) for the measurement of the shape and size of the planet Earth. The measurement of the arc is an exceptional example of different countries scientists’ and monarchs’ cooperation with a scientific aim. The length of the arc is 2,820 km. When the arc was created and more than a century later it was the longest measured meridian arc. It passes through the territory of today’s Norway, Sweden, Finland, Russia, Estonia, Latvia, Lithuania, Belarus, Moldova and Ukraine. The original arc consisted of 258 main triangles and 265 main station points. Thirty-four of the original station points today survive, and three of them are situated in Estonia, one in the Tartu Observatory and two in Simuna in the West-Viru County. Since 2005 the Struve Geodetic Arc is a UNESCO world heritage site.
Struve was born at Altona 15.4 1793, in what is now Germany, the son of Jacob Struve (1755–1841), and was the second of an entire family of astronomers through five generations. He was the great-grandfather of Otto Struve and the father of Otto Wilhelm von Struve. He was also the grandfather of Hermann Struve, who was Otto Struve's uncle.
In 1808 he entered the University of Tartu in the Russian Empire, where he first studied philology, but soon turned his attention to astronomy. From 1813 to 1820 he taught at the university and observed at Dorpat Observatory in Tartu, and in 1820 became a full professor and director of the observatory.
Friedrich Georg Wilhelm von Struve remained at Tartu, occupied with research on double stars and geodesy until 1839, when he founded and became director of the new Pulkovo Observatory near St Petersburg. Among other honors, he won the Gold Medal of the Royal Astronomical Society in 1826. He retired in 1861 due to failing health. He died 23.11.1864.
Fun facts about the Old Observatory
1. Where did they initially want to build the Observatory?
At first they wanted to construct it in the towers of Tartu Cathedral, which was also the home of the University Library. This would have meant that the stars of the sky and of literature would be under the same roof.
2. What connects the island of Naissaar to a NASA space probe named after Kepler?
Naissaar was the birthplace of astro-optician Bernhard Schmidt who became famous for inventing the Schmidt telescope, which corrected optical errors and had a wide-angle camera and short exposure time. The most remarkable of Schmidt’s telescopes are the LAMOST in China (the largest in the world) and the NASA space probe Kepler, which started its mission to find habitable planets on March 6, 2009.
3. What connection does Friedrich G. W. Struve’s great grandson Otto Struve have with extraterrestrial intelligence?
A space radio signal was first discovered in 1931 when researching radio frequency disturbances in a shortwave. They discovered that in addition to atmospheric disturbances there was also a disturbance that had a periodically changing intensity and equalled the length of a stellar day. This means that the source of the radio signal is not only outside the Earth’s atmosphere but comes from outside our Solar System. The main research objects of radio astronomy were those parts of the galaxy that were located behind cosmic dust clouds and could not be observed with optical equipment. They began looking for signs of extraterrestrial radio signals, which might suggest the existence of extraterrestrial intelligence in the Universe, after 1959 when Nature magazine published an article by Guiseppe Cocconi and Philip Morrison, which stated that radio telescopes could also be used to trace alien radio signals. Academic circles were very sceptical about this at first. The first director of the US National Radio Astronomy Observatory who actively supported the search for signs of extraterrestrial civilizations was Friedrich G. W. Struve’s great grandson Otto Struve (1897–1963).
4. How did an observatory servant Martin Saar obtain a quick promotion in the Observatory in the 19th century?
He accompanied Johann Heinrich Mädler, Director of the Observatory, on his expedition in Spain. Since he assisted the professor in his experiments, he was marked in the report as an assistant and not a servant.
5. Which place in Tartu first received an internet connection?
The Old Observatory entered the Age of the Internet in 1992 when a satellite receiver was installed here by order of Estonian Biocentre. It was the first internet connection in Tartu, which enabled the establishment of the Estonian Education and Research Network EENet, which was located in the Old Observatory in 1993–2000.
6. What connects the Old Observatory to genetics?
Two institutions that began their work in the Old Observatory in 1986, the Institute of General and Molecular Pathology of the University of Tartu and the Institute of Chemical and Biophysics of the Academy of Sciences, initiated the founding of Estonian Biocentre, which develops gene and cell technologies.
7. Why did the professors of the University of Tartu buy the freedom of a Latvian serf in 1805?
The Latvian boy Karl Williams was freed by the professors of the University of Tartu for his “outstanding talent in mechanics” and to “give him a future of freedom and science”. The first Director of the Observatory, Johann Wilhelm Andreas Pfaff, had Williams constructing a small transit instrument in 1804–1805, which is believed to be the first astronomical instrument ever made in Tartu.
8. Which Estonian author’s book has a character based on Bernhard Schmidt?
Jaan Kross’ novel Sailing Against the Wind was inspired by the life of world renowned astro-optician Bernhard Schmidt. He was born on the island of Naissaar to a ship pilot and showed a lot of promise as an engineer already in his youth. He polished lenses, constructed a spyglass and photo camera, which he used to take pictures of his relatives and the inhabitants of Naissaar. At the age of 15, he lost his right hand as a result of a gunpowder experiment gone wrong. For this reason he would never become a fisherman. He dedicated the rest of his life to astronomy and optics. In 1930, when working as master optician in Hamburg Observatory, Bergedorf, Schmidt constructed a reflector telescope which corrected for optical errors and had a very large wide-angled view and short exposure time – the Schmidt camera. The invention was so original that it astounded opticians around the world. It is considered one of the most remarkable achievements in instrumental optics to this day. B. Schmidt’s handiwork can be admired in the Old Observatory exhibition.
9. Which Tartu astronomer’s family has had the most children?
Friedrich G. W. Struve had the most children. l2 children with his first wife Emilie and 6 children with his second wife Johanna: altogether 13 sons and 8.50 daughters. In addition to his own children, Friedrich also raised his nephew Theodor.
10. Why does the Fraunhofer Refractor “deserve” its name?
Refracto is Latin for “I break”. Baron Wilhelm Wrangell broke his leg near Valga when the telescope was being transported and Struve broke his leg on one of his observation nights when moving around the telescope.
11. Why would making X-rays disrupt the rail traffic of the Republic of Estonia?
In the 1920–1930s, the Observatory was not responsible for measuring the right time itself but received the right time from other observatories via radio signals. However, receiving these signals was not always easy since the X-ray machines of the clinic next door disrupted the radio signals. As it happened, on some days, Estonia did not receive the right time.
12. Which director of the Observatory has been suspected of being a foreign spy?
During the War of 1812, a Russian army patrol accused Friedrich G. W. Struve of being a French spy when they saw him surveying. At the time, he was trying out the Troughton sextant he had purchased with his own money. The situation was resolved in Pärnu military court and all charges against Struve were dropped.
13. Which object in the Observatory comes from the land of 1001 nights?
The Arabic celestial globe, which was constructed some time between 1250 and 1350 in the lands of an Arabian caliphate. The globe exemplifies the wisdom of Arabian astronomers.
14. Which scientific instrument has been to the summit of Mount Ararat?
The Reichenbach-Ertel astronomic theodolite accompanied Professor Parrot on the world’s first science expedition to Mount Ararat. The astronomic theodolite was used to measure the longitude and latitude of the observation sight.
15. How did a post-party observation make a Tartu astronomer world famous?
On August 20, 1885, during an evening gathering at the home of UT astronomer-observer Hartwig, guests began arguing over the widely accepted theory that a star is formed when a gas cloud is compressed. After a lively discussion, Hartwig’s friends all developed a keen interest in the mystical nebulas and the group decided to go and observe one of them, even though there was a full moon in the sky. Hartwig located the great nebula in the Andromeda constellation. Instead of seeing a small blurry patch, which would have appeared to have a spiral structure during a darker night, Hartwig saw a new star. It had to be the new star that Laplace had predicted. Hartwig had observed Andromeda a few weeks before so he was sure this was a new body. His discovery “A very strange change in the Great Andromeda Nebula. A fixed-star-like core, (star) size seven” was quickly forwarded to Kiel’s astronomy information centre, which registered the message and soon received many other similar messages. This star has later been identified as the first registered supernova outside the Milky Way galaxy.