Research areas:
the magnetohydrodynamics group as part of the astrophysical institute potsdam
works on problems in cosmic magnetohydrodynamics.
About:
Origin
The history of astronomy in Potsdam really began in Berlin in 1700. Initiated
by Gottfried W. Leibniz, on July 11, 1700 the 'Brandenburgische Societät' --
the later Prussian Academy of Sciences -- was founded by the elector Friedrich
III. in Berlin. Two months earlier the national calendar monopoly provided the
funding for an observatory. By May 18 the first director, Gottfried Kirch, had
been appointed. This happened in a hurry, because the profits from the national
basic calendar, calculated and sold by the observatory, should have been the
financial source for the academy. This kind of financing existed until the
beginning of the 19th century, but the basic calendar was calculated until very
recently --- it passed away after the 'Wende' in 1991.
In 1711 the first observatory was built in Dorotheen Street in Berlin and in
1835 a new observatory building, which was designed by the famous architect
Karl Friedrich Schinkel, was completed in Linden Street (near Hallesches Tor).
Alexander von Humboldt was then promoting astronomy by his famous 'Kosmos'
lectures in 1827/28. He played an important role in providing the funds for
both observatory and instruments.
The Berlin Observatory became known world-wide when Johann Gottfried Galle
discovered the planet Neptune in 1846. The discoveries of the canal rays by
Eugen Goldstein in 1886 in the physical laboratory of the observatory and of
the variation in the altitude of the Earth's pole by Karl Friedrich Küstnerr in
1888 were likewise important.
The last two scientific events took place when Wilhelm Julius Foerster was
director of the observatory, which was meanwhile attached to the University of
Berlin. He prepared the basis for the astronomical observatories in Potsdam: in
1874 the foundation of the Astrophysical Observatory Potsdam on the
Telegrafenberg and in 1913 the removal of the Berliner Observatory to
Babelsberg.
Foundation of the Astrophysical Observatory Potsdam
In the middle of the 19th century spectral analysis was developed by Gustav
Kirchhoff and Robert Bunsen. It provided the possibility of obtaining
information on the physical parameters and chemical abundances of stars, by the
spectral analysis of their light. Foerster recognized these possibilities and
initiated the building of a solar observatory. in 1871 as a memorial to the
crown prince, in which he emphasized the importance and profit of solar
research, This idea was soon extended to the whole astrophysics.
The site of the observatory was chosen on a hill south of Potsdam, the
Telegrafenberg, on which had been, from 1832 to 1848, a relay station of the
telegraph for transmission of military information from Berlin to Koblenz. On 1
July 1874 the Astrophysical Observatory Potsdam was founded. Even before the
construction of the observatory had started in the autumn of 1876, solar
observations were being made from the tower of the former military orphanage in
Linden Street in Potsdam by Gustav Spörer. The construction work started in
1876, and the main building of the observatory and its equipment were finished
in the autumn of 1879.
The AOP was managed by a board of directors comprising Wilhelm Julius Foerster,
Gustav Kirchhoff and Arthur Auwers. In 1882 Carl Hermann Vogel was appointed as
sole director of the observatory. The main focus of his work was now on stellar
astrophysics. He was the first successfully to determine radial velocities of
stars photographically and as a result he discovered the spectroscopic
binaries.
In 1899 what was then the largest refractor in the world, with lenses of 80 and
50~cm, manufactured by the firms of Steinheil and Repsold, was mounted in a
24~m dome. It was inaugurated in a great celebration by the German emperor,
Wilhelm II. Although the Great Refractor of Potsdam did not realize all the
hopes astronomers had for it, nevertheless two important discoveries should be
mentioned: the interstellar calcium lines in the spectrum of the spectroscopic
binary delta Orionis by Johannes Hartmann in 1904 and the presence of stellar
calcium emission lines -- a hint on stellar surface activity -- by Gustav
Eberhard and Hans Ludendorff about 1900.
Ten years later one of the most famous astrophysicists of this century, Karl
Schwarzschild, became director of the observatory. In only a few years of work
-- by 1916 he had died after a insidious illness -- he had made fundamental
contributions in astrophysics and to General Relativity Theory. Only some weeks
after publication by Einstein of his General theory, Schwarzschild found the
first solution of the very complicated system of Einstein equations, which is
now named after him as the 'Schwarzschild solution' and which is of fundamental
importance for the theory of black holes.
There exist further close links between the AOP and Einstein's Relativity
Theory. In 1881 Albert A. Michelson performed his experiments in an attempt to
demonstrate the movement of the Earth through the hypothetical ether, in the
cellar of the main building of the AOP. His negative results were fundamentally
reconciled only through Einstein's Special Relativity Theory of 1905.
To prove the redshift of spectral lines in the gravitational field of the sun
-- an effect proposed by Einstein's GRT -- was the aim of a solar tower
telescope, which was built from 1921 to 1924 at the instigation of Erwin
Finlay-Freundlich. Though at that time it was not yet possible to measure the
gravitational redshift, important developments in solar and plasma physics were
started here and the architect, Erich Mendelsohn, created with this peculiarly
expressionistic tower a unique scientific building.
Besides the work of Schwarzschild, in the following decades important
observational programmes such as the ''Potsdamer Photometrische
Durchmusterung'' and the outstanding investigations of Walter Grotrian on the
solar corona found recognition all over the world.
Relocation of the Berlin Observatory to Babelsberg
At the end of the 19th century the Berlin Observatory, originally built outside
the border of the town, was enclosed by blocks of flats and scientific
observations were almost impossible. Therefore, Foerster proposed the removal
of the observatory to a place with better observational conditions outside
Berlin. In 1904 he appointed Karl Hermann Struve, former director of the
observatory of K"onigsberg, as his successor to realize this project.
After test observations by Paul Guthnick in the summer of 1906 a new site was
found on a hill in the eastern part of the Royal Park of Babelsberg. The ground
was placed at the observatory's disposal by the crown free of charge. The costs
of the new buildings and the new instruments amounted to 1.5 million Goldmark
and could be covered by selling the landed property of the Berlin Observatory.
The old observatary built by Schinkel was pulled down later. In June 1911 the
construction of a new observatory began in Babelsberg and on 2nd August 1913
the removal from Berlin to Babelsberg was complete.
The first new instruments were delivered in the spring of 1914. The 65 cm
refractor -- the first big astronomical instrument manufactured by the famous
enterprise of Carl Zeiss Jena -- was mounted in 1915, whereas the completion of
the 120 cm mirror telescope was delayed until 1924 as a result of the First
World War. Struve died in 1920 from an accident, and his successor was Paul
Guth\-nick, who introduced in 1913 photoelectric photometry into astronomy as
the first objective method of measuring the brightness of stars. When the 120
cm telescope -- at this time it was the second largest in the world -- was
finished, the Babelsberg Observatory was the best-equipped observatory of
Europe.
The development of the photoelectric method for investigating weakly variable
stars and spectroscopic investigations with the 120 cm telescope made the
Babelsberg observatory well-known beyond Europe, too.
At the beginning of 1931 the Sonneberg Observatory founded by Cuno Hoffmeister
was attached to the Babelsberg Observatory. For more than 60 years a
photographic sky survey was carried out, which represents the second largest
archive of astronomical photographic plates. This archive and the discovery and
investigation of variable stars popularized the name Sonneberg all over the
astronomical world.
With the beginning of the regime of fascism, the fortunes of astronomy in
Potsdam as well as in Babelsberg started to decline. The banishment of Jewish
co-workers played an essential role in this process. The beginning of the
Second World War practically marked the cessation of astronomical research.
Development after the Second World War
The new start after the war was very difficult. In Potsdam the Einstein Tower
had suffered heavy damage by bombs, in Babelsberg valuable instruments, among
them the 120 cm telescope, were dismounted and removed to the Soviet Union as
war reparations.
In January 1947 the German Academy of Sciences took the Astrophysical
Observatory Potsdam and the Babelsberg Observatory under its administration,
but it was not until the beginning of the 1950s before astronomical research
started anew.
In June 1954 the Observatory for Solar Radio Astronomy in Tremsdorf (17 km
distant south-east from Potsdam) began its work as a part of the AOP. The
history started in 1896: after the discovery of the radio waves by Heinrich
Hertz in 1888, Johannes Wilsing and Julius Scheiner, fellows of the AOP, tried
to detect radio emission from the Sun. They did not succeed, because of the low
sensivity of their equipment. After the Second World War Herbert Daene started
once again to attempt radio observations of the Sun at the site of Sternwarte
Babelsberg and these were continued in Tremsdorf. In October 1960 the 2m
telescope built by Carl Zeiss Jena was inaugurated in the Tautenburg Forest
near Jena and the new Karl Schwarzschild Institute was founded. The Schmidt
variant of this telescope is up to now the largest astronomical wide-field
camera in the world and it was the main observational instrument of the
astronomers of the GDR.
In 1969 the four East-German astronomical institutes, Astrophysical Observatory
Potsdam, Babelsberg Observatory, the Thuringian Sonneberg Observatory, and
Karl-Schwarzschild Observatory Tautenburg, were joined in the course of academy
reform to the Central Institute of Astrophysics of the Academy of Sciences of
the GDR. The Solar Observatory Einstein Tower and Observatory for Solar Radio
Astronomy were affiliated later.
One part of the scientific activities concerned cosmic magnetic fields and
cosmic dynamos, phenomena of turbulence, magnetic and eruptive processes on the
Sun, explosive energy dissipation processes in plasmas, variable stars and
stellar activity. Another part was directed to the early phases of cosmic
evolution und the origin of structures in the Universe, large-scale structures
up to those of superclusters and to active galaxies. In this connection special
methods of image processing have been developed. In addition, investigations in
astrometry have also been performed.
The scientific work of the Zentralinstitut für Astrophysik suffered strongly
from the isolation of the GDR from the western world. It was very difficult to
come into contact with western colleagues. When in the autumn of 1989 the
'Wall' was demolished, new possibilities at once arose.
On the basis of the prescriptions of the 'Einigungsvertrag' for the Academy of
Science of the GDR, the Central Institute of Astrophysics was dissolved on 31st
December 1991. On the recommendation of the Wissenschaftsrat on 1st January
1992 the Astrophysical Institute Potsdam, with a greatly reduced staff, was
founded. The Sonneberg Observatory and the Karl Schwarzschild Observatory
Tautenburg are no longer affiliated to the Astrophysical Institute Potsdam.
Address:
Prof. Dr. G. Rüdiger
An der Sternwarte 16
D-14482 Potsdam
+49 (0)331 7499512
E-mail: gruediger@aip.de
Website: www.aip.de/groups/MHD/
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