On your right, look for a pale yellow brick, three-winged building anchored by a distinctive green dome and a bronze statue standing proudly in front.
Back in the early nineteenth century, Copenhagen's original observatory, the Round Tower, had a serious problem. Telescopes were getting massive, and a stone tower simply could not stretch to accommodate them. Worse, increasing horse-drawn traffic was causing tremors, and city lights were ruining the dark skies.
So, in eighteen sixty-one, they moved the operation here, to the city's abandoned defense fortifications. The architect, Christian Hansen, designed this elegant south-facing building, but the real engineering genius is buried deep underground.
Telescopes absolutely hate vibrations. To keep the massive central instrument perfectly still, Hansen ran the foundation all the way through the artificial dirt of the old ramparts to hit the true, solid ground beneath. That invisible, vibration-killing anchor used up one third of all the bricks required for the entire complex. You can check your screen to see the scale of the central dome that foundation had to support.
Inside that dome sat a powerful refractor telescope, which is a telescope that uses long glass lenses instead of mirrors to focus light. The observatory's first director, Heinrich Louis d'Arrest, used it to map nearly two thousand nebulas, those massive, glowing clouds of dust and gas in deep space.
Meanwhile, an observer named Schjellerup used a meridian circle, a specialized telescope fixed to only move up and down, to track the exact timing of stars crossing the sky. Over two hundred and fifty-nine nights, he logged ten thousand star positions.
This place was a heavy hitter in global astronomy. During World War One, the Central Bureau for Astronomical Telegrams moved here from Germany. For decades, this very building acted as a cosmic switchboard, managing the global flow of astronomical discoveries until nineteen sixty-five.
The crowning achievement came from director Bengt Strömgren in the mid-twentieth century. He made the pioneering discovery that the interior of a star is mostly made of hydrogen. It was a massive leap forward in astrophysics.
Eventually, the city grew too bright again. In the nineteen fifties, the heavy astronomy work was relocated to the darker countryside, and today, this beautiful old brick fortress of science houses the Institute for Science Didactics.
Appreciate the quiet weight of this scientific fortress. When you are ready, we will continue our walk.
