Look Through the Telescope
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31.03.2027
Look Through the Telescope
Get closer to both the heavens and history and try looking through the telescope every Monday and Tuesday during the winter season.
The observatory season begins in October. Every Monday and Tuesday from 18:00 to 21:00, you can step beneath the newly restored copper dome and observe the Moon or planets* through the historic telescope, which has been finely calibrated by experts in Germany with the assistance of our skilled astronomers.
Admission to the observatory is free once you have paid the entrance fee to the tower.
Please note: The Round Tower cannot guarantee that celestial objects will be visible if weather conditions do not permit observation. However, if the weather is unfavorable, visitors are still welcome inside the observatory, where our astronomers will instead share fascinating insights into the historic dome, the universe, and the telescope itself, which offers magnification ranging from 80× to 450×.
What can you observe in the sky?*
Here you can get an overview of which celestial objects we expect to be able to observe through the telescope — *provided the weather is clear and the sky is free of clouds and rain.
The Telescope
he Round Tower’s 1929 refracting telescope provides magnifications ranging from 80 to 450 times. It was built by the company Cornelius Knudsen and is particularly well suited for observing the planets, the Moon and the Sun.
The Main Telescope
The main telescope, dating from 1929, is a 150 mm refractor with a focal length of 2,250 mm. The telescope is three metres long and was designed and built by the Danish company Cornelius Knudsen. It is optimised for observing the planets and the Moon despite the light pollution of the city.
The Secondary Telescope
The secondary telescope, dating from 1980, is a 100 mm Unitron refractor with a focal length of 1,500 mm. Among other things, it is used to view the Moon in its entirety while the main telescope is used to observe it in greater detail.
The Camera
The camera is an 80 mm Goerz glass-plate camera from 1929, which was formerly used to observe new or previously unknown objects in the sky, such as comets and asteroids.
The Sun Telescope
The solar telescope was added around the year 2000. It allows visitors to observe prominences — plasma extending out from the surface of the Sun.
The Clock
The clock automatically rotates the telescope to compensate for the Earth’s rotation. The clockwork mechanism was created in 1929 by the renowned Danish clockmaker Jens Olsen.
The Time Capsule
A time capsule was placed in the base of the telescope in 2026 as part of the restoration of the People’s Observatory. It is filled with messages from Danes to the future, as well as ten of the greatest unanswered questions about the universe in our time. It is not to be opened until 2126.
History of the Observatory
The Round Tower was originally known as Copenhagen’s Royal Star Castle. Over the centuries, a number of different structures have stood atop the tower to house its astronomical instruments.
The present-day Public Observatory dates from 1929 and is opened on selected days, allowing all visitors to the Round Tower to observe celestial objects through its large refracting telescope in clear weather. The telescope was built in part by Jens Olsen, the renowned clockmaker who also created the clock of the Copenhagen City Hall.
