History
Leiden University is the oldest university in The Netherlands. In 1574, Prince William of Orange took the first step towards establishing the university, as a reward for the city's brave resistance to the Spanish besiegers. The university was founded on February 8, 1575. Throughout the centuries many great scholars and scientists have brought fame and respect to Leiden University.
Astronomy in Leiden has a long tradition. In 1633, Leiden University
established an observatory to
accommodate the so-called
quadrant of Snellius
(the Dutch scientist best known for his laws of refraction). This founding
date makes the Sterrewacht Leiden the oldest still operating university
observatory in the world. In the first two centuries of its existence it
served mainly an educational purpose. The construction of a
spacious new observatory building
in 1861, under the supervision of
F. Kaiser, marks the
beginning of the modern era of astronomical research in Leiden. This
building was the home of Leiden astronomy for over a century, and still
has powerful symbolic value.
Already in the late 19th and early 20th century Leiden
was an exciting place to work, in the vicinity of many famous physicists, such
as
H.A. Lorentz,
P. Zeeman,
P. Ehrenfest, and
H. Kamerlingh Onnes. In 1919
W. de Sitter
became director of the Observatory. He added an astrophysical
(spectroscopy and photometry of stars) and a theoretical division to the
existing astrometric one. De Sitter himself was head of the
Theoretical Division and among other things worked with Einstein on the
cosmological implications of general relativity. The head of the Astrophysical
Division and the successor of De Sitter as Observatory Director was
E. Hertzsprung,
famous as co-inventor of the Hertzsprung-Russell diagram of
stars, a tool still widely used today.
In 1924 de Sitter brought to Leiden the man who would become the most famous of
all Leiden astronomers,
J.H. Oort.
Oort worked on the motions of stars
relatively close to the Sun and discovered the rotation of our Galaxy. In 1945
Oort succeeded Hertzsprung as Observatory Director and he remained in
office until his retirement in 1970. Few astronomers have made so many
important contributions to so many different fields in astronomy as
Oort has.
His interests range from comets (the Oort cloud) and our Solar System, to
stars, galaxies (the Oort constants), clusters and the large-scale structure
of the Universe. In 1944 he encouraged a student from Utrecht,
H.C. van de Hulst,
to calculate whether neutral hydrogen could produce observable
radiation. Van de Hulst predicted that the 21-cm hyperfine ``spin flip''
transition might be observable because of the large number of hydrogen atoms
expected along a line-of-sight through the Galaxy.
The detection in 1951 at Harvard by Ewen and Purcell, confirmed within a
few weeks in the Netherlands by Muller and Oort, and in Sydney by Pawsey,
marked the birth of spectral-line radio astronomy. Van de Hulst later became a
professor in Leiden and has worked on a range of problems concerning
interstellar dust and radiative transfer. Oort was also one of the founding
fathers of the
European Southern Observatory,
established in 1962. Four of the most recent directors of ESO,
A. Blaauw, L. Woltjer, H. van der Laan, and Tim de Zeeuw
were all Leiden professors.
In 1974 Leiden Observatory moved from Kaiser's old Observatory building
to the Huygens Laboratory, and recently to the new
J.H. Oort building.
The name Sterrewacht Leiden was kept. Now, astronomy is done with modern
means and the
Institute has become larger than ever before, still standing at the forefront
of astronomical research.
ALBUM AMICORUM
One of the largest books in the Leiden University collections is a monumental Album Amicorum for H.G. van de Sande Bakhuyzen (1828-1923). It was presented to him when he retired as professor of astronomy at Leiden University in 1908. The album contains hundreds of photos of scientists, observatories and telescopes from around the world. It provides a unique overview of the global astronomical community at the beginning of the twentieth century. The original album is preserved in the Library of Leiden University.
Oort Foto's
In combination with the book: The Letters and Papers of Jan Hendrik Oort, author Jet Katgert-Merkelijn has compiled a web page with astronomical group photographs containing J.H. Oort.