Federal observatory

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Federal Observatory (ETH Observatory)
ETH observatory.jpg

Main building (Semper Observatory)

Consist 1862-1980
Type Observatory
Coordinates 47 ° 22 '41 "  N , 8 ° 33' 1.9"  E Coordinates: 47 ° 22 '41 "  N , 8 ° 33' 1.9"  E ; CH1903:  683968  /  248065
place Zurich

The former Swiss Federal Observatory in Zurich (also known as the Semper Observatory ) was designed and built by the architect Gottfried Semper for the Swiss Federal Polytechnic (today ETH Zurich ). It is located at Schmelzbergstrasse 25 near the main ETH building.

The observatory was in operation from 1862 to 1980. It is of importance in the history of astronomy because of its achievements in researching sunspots . That is why it was declared an Outstanding Astronomical Heritage by the International Astronomical Union .

The Swiss Federal Observatory is the only building that Semper owned that has barely been damaged over time and is therefore considered a monument of national importance .


Federal Observatory (1889)

Semper was the first architecture professor at the newly founded Polytechnic. The foundation stone for the observatory was laid on March 27, 1862, and it was completed in 1864.

The first director of the observatory was Rudolf Wolf . The long-term observation of sunspots was started on his initiative. Later , the observatory coordinated the international observation of sunspots and published the Zurich Sunspot Number (wolf number, sunspot relative number) , which is still the standard today.

Between 1910 and 1911 the small observatory was built on the edge of the observation terrace. In 1950/51 the solar observation tower was built.

From 1939 to 1980, the observatory also operated the astrophysical observatory on the Tschuggen in Arosa (not to be confused with the light-climatic observatory that has been there since 1921, which has carried out ozone measurements) and, from 1957, the Specola Solare in Locarno- Monti, which is still active today .

From 1945 the astronomical observation possibilities were severely restricted because of the newly built Canton Hospital (today: University Hospital Zurich ). The observatory ceased operations on April 1, 1980.

The observatory has had four directors throughout its history:

Between 1989 and 1993 the area between the observatory and the cantonal pharmacy was redesigned, and from 1995–1997 the facility was extensively restored.

The building now houses the Collegium Helveticum , an interdisciplinary research institute at ETH Zurich.

See also


  • Thomas K. Friedli, Martin Fröhlich, Adolf Muschg, Hanspeter Rebsamen, B. Schnitter: Semper's former Swiss Federal Observatory in Zurich. ( Swiss Art Guide , No. 631/632, Series 64). Swiss Society for Art History SGK. Bern 1998, ISBN 3-85782-631-2 .

Web links

Commons : ETH Zurich observatory  - collection of images, videos and audio files

Individual evidence

  1. a b c d e f Semper Observatory. collegium.ethz.ch.
  2. Top research on the house roof - Arosa's hidden laboratory . In: Neue Zürcher Zeitung from January 18, 2016.