Uraniborg: An Observatory Without a Telescope

Before the invention of the telescope, astronomers relied on a variety of tools and techniques to observe and study the celestial objects and phenomena. The simplest and the most ancient method was unaided observation with the naked eye. However, early astronomers extended their observational capabilities through a variety of instruments like the astrolabe, quadrant, sextant, and armillary sphere. One of the last major astronomers who harnessed these tools to achieve remarkably precise astronomical observations was Danish astronomer Tycho Brahe.

Tycho Brahe's Uraniborg observatory.

Tycho Brahe was arguably the greatest observational astronomer to live before telescopes were invented. Brahe was known for his meticulous and precise observations of celestial objects and events. He collected extensive data on the positions and motions of planets and stars, far more accurate than any observations made before him. Brahe compiled the first comprehensive and accurate star catalog, containing the positions of over 1,000 stars. This catalog served as a reference for later astronomers and contributed to the improvement of navigation and celestial mapping. In 1572, Brahe observed a supernova in the constellation Cassiopeia. This event challenged the prevailing Aristotelian view that the heavens were unchangeable and showed that celestial objects could change over time. Tycho Brahe's most lasting contribution was his collaboration with the German mathematician and astronomer Johannes Kepler. After Brahe's death, Kepler used his precise observational data to formulate his famous three laws of planetary motion. These laws became the foundation for Isaac Newton's law of universal gravitation.

To reward Brahe for his service, in 1576, King Frederick II of Denmark offered the astronomer the small island of Hven in the Öresund strait as a place to conduct his studies into astronomy and chemistry. Using his independence and financial security, Brahe established an observatory called Uraniborg on the island. It was the first time that a building was erected in Europe especially for the purpose of astronomical observations. It was also one of the last observatories built before the development of the telescope.

The main building of the observatory.

Completed in 1580, the sandstone and limestone-framed brick building was erected in the style of the Flemish Renaissance by the Danish architect Hans van Emden and sculptor Johan Gregor van der Schardt in close cooperation with Brahe. The main building was surrounded by a walled garden, approximately 15 meters square with a semicircular tower built on each of these walls. The plan and façade of the building, and also the plan of the surrounding gardens, were designed on grids, with proportions that Tycho carefully specified. These proportions may have been intended to make Uraniborg function as an astrological talisman, benefiting the health of its occupants by increasing the influences of the sun and Jupiter.

The main building was three storied. The ground floor was occupied by Brahe and his family, as well as by visiting astronomers. The northern tower housed the kitchens, and the southern a library. In this library and within Brahe's personal study was etched the motto "Non haberi sed esse," which translates from Latin to "What one is, is more important than what one is perceived to be.”

Various astronomical instruments at Uraniborg.

The second floor housed the primary astronomical instruments, accessed from outside the building or from doors on this floor. Balconies, supported on wooden posts, housed additional instruments slightly further from the building, giving them a wider angle of view. The third floor rooms were for students. Uraniborg also had a large basement where Brahe established an alchemical laboratory.

The entire complex was surrounded by a large earth mound. That mound is the only remnant of the observatory still in place. After the death of King Frederick II, Brahe lost financial support forcing him to abandon Hven in 1597. Brahe died in 1601, and shortly after the new king, Christian IV, destroyed Uraniborg and another astrological site that Brahe had built, called Stjerneborg.

Uraniborg and Stjerneborg were partly excavated in the 1950s. The site now includes a restored quarter of Brahe's original garden with plants and herbs laid out in beds that are also boxed in with a wooden fence. A fruit orchard was also placed within the center of the pavilion. The refurbished structure of Uraniborg and Stjerneborg have been incorporated into a museum dedicated to Tycho Brahe.