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Middle-Age Astronomy

The "Wiener Mathematische Schule":
Early Astronomy in Vienna

In the early Middle Ages, natural science stagnated in Europe, while Arab mathematicians and astronomers contributed enormously to scientific improvement. The foundation of the new universities (e.g. Vienna 1365) brought science back to Europe.

A first golden age of astronomy in Austria is related to three important scientists:

  • Johannes von Gmunden (1385 - 1442),
  • Georg Aunpeckh von Peuerbach (1423 - 1461),
  • and Johannes Müller von Königsberg ("Regiomontanus", 1436 - 1476).

Johannes von Gmunden, capitular of St. Stephen's cathedral, Vienna, focused on planet track observation, instrumental development, and calendars. His successor Peuerbach, travelled to Italy and came into contact with Islamic immigrants, who brought oriental expertise to Europe after the fall of Konstantinopel (1453). One of Peuerbach's major achievements was the introduction of trigonometry to the Western World. Unfortunately, his translation of the Almagest was terminated by an early death at the age of 38. Some of his work was completed by his excellent student Regiomontanus, who was mainly biased on meteorology, translations of classical literature, calendars, and other fields of mathematical astronomy. His "Ephemeris" (1474) played an important part in the history of the world, as used for navigation by Columbus.


From left to right:
The University of Vienna was founded in 1365
(GIF 233 kB).
Middle-age view of Vienna, with St. Stephen's cathedral
(GIF 119 kB).
Johannes Müller von Königsberg ("Regiomontanus", 1436 - 1476)
(GIF 101 kB).
Eclipse tables by Regiomontanus (reprint)
(GIF 76 kB).

The Copernican Revolution

Following and completing some of the considerations by Regiomontanus, Nicolaus Copernicus (1473 - 1543) and the Austrian Johannes Kepler (1571 - 1630) proved the validity of heliocentrism by theory and observations. This became the basis of modern astronomy. Their most important publications are "De revolutionibus orbium coelestium" and "Astronomia nova".


From left to right:
"De revolutionibus orbium coelestium" by Copernicus, front page
(GIF 133 kB).
Schematic diagram of the Solar system according to Copernicus (from "De revolutionibus orbium coelestium")
(GIF 110 kB).
"Astronomia nova" by Johannes Kepler, front page
(GIF 90 kB).
Click to enlarge.

First Observatories in Austria

Marinoni's Private Observatory

Although astronomy was tought at the University of Vienna from the Middle Ages on, even in the early 18th century, there was no institute with a permanent observatory in Vienna. The mathematician Johann Jakob de Marinoni from Udine, Italy (1676 - 1755), established the first observatory of Vienna in 1730 on the roof of his private house.


From left to right:
Vienna, early 18th century
(GIF 86 kB).
The engaged observer Johann Jakob de Marinoni at his inconvenient work
(GIF 184 kB).
Front page of the detailed description of Marinoni's private observatory
(GIF 157 kB).

The "Astronomical Tower" of the Jesuits

Only a few years later (1733), the Jesuits built a 45-meter tower containing an obervatory. Today, the majority of the most valuable books owned by the University of Vienna is thanks to the passionate collectorship of the Jesuits.

View of the inner city of vienna (mid 18th century) with the "Astronomical Tower" of the Jesuits in the background (GIF 183 kB).

The First Observatory of the University

In January, 1755, shortly before the construction of the new university building (today: Austrian Academy of Sciences) was finished, Marinoni died. The equipment of his private observatory became property of the empress Maria Theresia, who made it available to the University. This gave reason to the construction of the first Vienna university observatory on the roof of the assembly hall. Planning was performed by the Jesuits.

The windows of the observatory tower were used for measurements of stellar positions using telescopes and sextants. High-precision pendulum clocks were required as well.


Left: the old university building, which now accomodates the Austrian Academy of Sciences (GIF 209 kB).
Right: interior view of the observatory in the tower of the old university
(GIF 93 kB).

Important Scientific Results

The first director of the observatory, the Jesuit Maximilian Hell (1721 - 1792), was internationally respetable, especially thanks to the editorial of astronomical ephemerides ("Ephemerides Astronomicae", 1757 - 1806), well before ephemerides were published at the prominent observatories at Greenwich and Berlin. The tables contained high precision positions of Sun, Moon, planets, and the brightest stars. In addition, Hell concentrated on the exact determination of geographic longitude.

The most spectacular event in his era was a rare Venus transit in front of the Sun, which he observed on the island of Wardoe in the Arctic Sea. In combination with other observations of this event, the distance between Sun and Earth was determined at an unpreceded accuracy, which held reference status for several decades.

Hell's successor, Franz de Paula Triesnecker (1745 - 1817) primarily concentrated on geodesy. Two central craters on the Moon are named after the first two directors of the observatory.

Soon the wooden construction on the roof of the university building turned out too light and unstable for the operation of an observatory. Especially vibrations due to horse-drawn vehicles and wind restricted the accuracy of astronomical measurements intolerably. In the early 19th century, this gave way to the desire for moving the observatory to a favourable place.


From left to right:
Maximilian Hell (1721 - 1792)
(GIF 136 kB).
Front page of the Venus transit expedition report by Maximilian Hell
(GIF 120 kB).
Impression of the Venus transit expedition by Hell: the last harbour before he reached the North Cape
(GIF 113 kB).
Triesnecker crater (25 kilometers diameter). To the east of this crater there is an extensive system of rilles extending over 200 kilometers
(GIF 98 kB).

Recent History

A New Attempt

A new era started in 1819, when Johann Josef von Littrow (1781 . 1940) became Professor of Advanced Mathematics and Astronomy at the University of Vienna. He put intensive effort in moving the observatory to the periphery - and did not succeed. After his death, his son Carl Ludwig von Littrow (1811 - 1877) became provisional director of the observatory. In his first year, a total Solar eclipse on July 8, 1842, fascinated a major part of the population and was a perfect promotion for new investments into astronomy. In 1872, a lot for the new observatory (55 000 m2) on a hill of the "Türkenschanze" could be purchased.


Left: total Solar eclipse (July 8, 1842) (GIF 209 kB).
Right: lot for the new observatory building (1872)
(GIF 93 kB).

The World's Largest Observatory

The cornerstone for the new observatory building was laid on July 19, 1874. Architects of the grand-scaled new building were Ferdinand Fellner and Hermann Helmer, both specialised in theatre buildings. The conception was a combination of a housing and an observing unit in a cross-shaped ground view. The dimensions are unusually large: 101 m long, 73 m wide (St. Stephen's cathedral measures 108x70.5 m). The installation of the big refractor telescope (68 cm = 27 inch aperture, 10.5 m focal length) made this observatory a top-class site of the 19th century. At the time of installation, the telescope was the largest in the world. The celebratory opening was on June 5, 1883, in the presence of emperor Franz Joseph I.; the first director was Edmund Weiss (1837 - 1917).

During the following years, the excellent instrumentation made possible numerous remarkable discoveries in the fields of binary stars, asteroids and comets. However, the obervatory was surrounded by illuminated urban area soon, since the environment became an attractive place to live for the Viennese upper-class population. Plans to establish an even larger observatory on the "Schneeberg" - a mountain at a distance of about 100 km from Vienna - failed due to the fall of the monarchy. Financial means were restricted for a long time. Although not damaged in the course of the World Wars, the maintenance of the observatory required all available resources, and a modernisation was barmedical.


From left to right:
Plan of the new observatory building
(GIF 91 kB).
View of the observatory, drawing by J.J. Kirchner, 1878
(GIF 187 kB).
View of the observatory, late 19th century
(GIF 162 kB).
Foundation of the new observatory by emperor Franz Joseph I.
(GIF 227 kB).
At the time of installation in 1883, the 27-inch refractor telescope was the largest in the world
(GIF 79 kB).

Modern Times

It was the "Wirtschaftswunder" after World War II to permit new investments into Austrian astronomy. Step by step, the personal as well as the instrumental situation were improved. In the 60s, even radio astronomy was performed on the roofs of the observatory. The height of this new period of promoterism was the establishment of an outpost on the "Mittelschöpfl". The Leopold-Figl Observatory for Astrophysics was opened in 1969. Today it contains two modern reflector telescopes with apertures of 1.52 m and 60 cm, respectively, and up-to-date instrumentation. Since the foundation of the observatory, the scientific effort switched towards astrophysics, which slowly superseded classical astronomy. One of the consequences of this development is the operation of two automatic photoelectric telescopes  in Arizona since 1996.


From left to right:
Radio dish on the roof of the observatory building
(GIF 99 kB).
Leopold-Figl Observatory for Astrophysics
(GIF 112 kB).
Interior view of the Leopold-Figl Observatory
(GIF 99 kB).


Towards the end of the 20th century, international contacts became more and more important in astronomy. Today, visits at observatories and institutes like the European Southern Observatory  - which Austria joined in 2008 - as well as the operation and participation in the construction of space telescopes are a substantial part of a Viennese astronomer's every day life.


Left: European Southern Observatory (GIF 54 kB).
Right: The infrared telescope Herschel  by the European Space Agency 
(GIF 87 kB).


F. Kerschbaum 





Monday, 9. October 2017

Bernhard Aringer (Padova):

Abundance Determination in Cool Giants
Monday, 18. September 2017

Gesa H.-M. Bertrang (Universidad de Chile):

On magnetic fields and what we can learn from polarimetry in protoplanetary disks
Monday, 11. September 2017

Kirill Kuzanyan (Moscow):

The solar and astrophysical dynamos and magnetic helicity
Monday, 4. September 2017

Alexandre David-Uraz (Univ. of Delaware):

Massive star winds interacting with magnetic fields on various scales
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