Tycho did his observations from his own observatory, Stjerneborg, on the island
of Hven. Hven is a low-lying island located between Denmark and Sweden. Tycho's
work was funded by King Frederick of Denmark. Tycho began construction in 1576.
Tycho observed before the invention of the telescope, using a collection of
quadrants and armillary spheres. He and his oberverving staff measured
positions of objects by measuring their altitudes as they crossed the meridian
(the declination) and the time they crossed the meridian (the right ascension).
While we are used to observatories located on mountaintops or, at least,
atop
tall buildings (where they can see over the ground clutter), Tycho
chose to build his observatory underground. He learned from experience,
because he first observed from the parapets of his castle Uraniborg, that
the seeing was poor just above the ground due to turbluence in the air flow.
Since Hven was (and is) flat, the air flow is laminar. So as not to disturb
it, be put his telescopes below ground, looking up through holes in a low
roof. This unusual choice resulted in an extremely stable observing site,
which contributed to the amazing precision of Tycho's measurements.
Drawing of the castle at Uraniborg | Plan of the observatory at Hven |
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I took the pictures below while on a visit to the Lund Observatory in Sweden in 2005. The island of Hven is a short ferry ride from the south of Sweden. The observatory has been reconstructed. There is a small museum devoted to Tycho's life. he was apparently a harsh taskmaster and ruled the island and its inhabitants (mostly farmers) as a tyrant.