Welcome to Sonnenborgh

Discover the secrets of Sonnenborgh. Go behind the thick walls of the 16th Century Bastion to search for cannon emplacements. Climb the stairs up to the 19th Century telescope domes and gaze at the stars. Imagine yourself as a meteorologist and carry out exciting weather experiments or take a close up view of the Sun with the aid of a special solar telescope. The observatory and meteorological institute were established in 1854 on top of the old Sonnenborgh bastion which dates back to 1552. Scientists conducted research into the weather, the stars and planets, as well as time measurement. Today Sonnenborgh is both a museum and an observatory, and there is still a great deal to see and do.

The Sonnenborgh Bastion
Experience the special history of a Utrecht bastion. Return to the 16th Century and seek out the canon emplacements in the casemates behind three metre thick walls. Take a peek into the old well, utilised as a latrine in the 16th Century. From 1998 to 2003 these fortifications were intensively studied and restored. Following the construction of the Zocher gardens in around 1840, a large portion of the bastion was buried underground. The entry gate was the first structure to be brought to light. The archaeologists then made further significant finds, such as a chemistry laboratory dating back to around 1700AD. Of all the bastions in Utrecht, Sonnenborgh has remained the best preserved. Even in comparison with other North European examples, it is in exceptionally good condition. Take a stroll past the unique spots of this 16th Century bastion and become acquainted with its long hidden secrets.

The Observatory (Sterrenwacht)
Sonnenborgh is the oldest cupola observatory in the Netherlands. There are four large telescopes with which to study the universe. Until 2002, the Merz Telescope from 1863 was the most important (night) telescope in the observatory. This instrument was one of the largest of its kind in the world. Today the computer-controlled Gala Telescope is the primary night telescope here. Activities include star viewing evenings, courses and special lectures. Come and take a look at the Moon and planets for yourself and pick out almost invisible gas nebulas.
Star Viewing Nights at Sonnenborgh

The Utrecht Meridian
For centuries many cities had their own observatory in order to ascertain the time. The stylish Meridian Room at the Sonnenborgh was also constructed for this purpose. Up until the start of the 20th Century, the stars were mapped to measure the passing of time, with the aid of a special telescope positioned on the Utrecht meridian. Come and check what the actual time is at longitude 5° 07' 46.67"!

Weather and Sun
The weather: everyone experiences it but anyone who wishes to find out more can do so at the Sonnenborgh museum and observatory. Meteorological research began here in the 19th Century. In 1854 the famous meteorologist C. Buys Ballot erected the KNMI (Royal Netherlands Meteorological Institute) and the observatory on top of the fortifications. As a researcher, Buys Ballot was a practical man: he oversaw the taking of measurements, introduced the weather forecast and aided shipping traffic with the provision of storm warnings, made visible with the use of a semaphore. He also brought about the cooperation of international meteorologists. How the weather was observed can be seen firsthand by the visitor through the historic instruments displayed in the collections of the KNMI and the University Museum. Can you remain standing during a force nine gale? And how is that related to Buys Ballot's Law? Test it out yourself and discover what comes into view through study of the weather.

At the Utrecht observatory one star has been examined very extensively, the Sun. Thanks to the Utrecht astronomers, we know what the Sun is made of and how hot it is. But how do you decipher the mysteries of a glowing hot ball of gas without going there? It is made possible with the special sun viewer or spectroheliograph. This instrument (the third example of its kind ever built in the world) consists of a 7 metre long telescope and behind it, a 12 metre long spectroscope. This splits up the light of the Sun into the colours of the rainbow. How this research works in practice and the ingenious inventions used for conducting it can be seen in the Weather and Sun Room. Wonder at the longest sun spectrum in the world and conduct experiments to discover which gases the Sun consists of.

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observatory
telescope positioned on the Utrecht meridian
weather and sun
© 2014 Sonnenborgh - museum & sterrenwacht
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