50th National Stargazing Days from February 27 to March 1, 2026

More than 60 member organizations of the KNVWS are established and active throughout the Netherlands. In addition, there are also independently operating organizations and individuals active in the field of meteorology and astronomy. Many of them participate to bring astronomy closer to the public during the National Stargazing Days. In 2025, visitors could visit 58 locations spread across the Netherlands.

50th National Stargazing Days

The 50th National Stargazing Days will take place during the weekend of February 27 to March 1, 2026. This annual event, organized by the KNVWS, offers the chance to look through telescopes, visit observatories, and attend lectures for free at over 50 to 60 locations in the Netherlands, often with special activities for children.

Important details:

Dates 2026: Friday, February 27, Saturday, February 28, and Sunday, March 1.

Locations: Spread throughout the country, including observatories and at local associations (such as in the Spoorpark Tilburg or the Oude Sterrewacht Leiden).

Activities: Looking at planets, constellations, and often the moon. In case of bad weather, there is usually an alternative indoor program.

Admission: Often free, but it is advisable to check the specific location for any registrations.

Check the website below for the full program and participating locations in your area.

 

The Old Observatory

Frederik Kaiser published a first design for an observatory in 1854 in the journal *Lectuur voor de Huiskamer*. His plan was not executed, but the proposal described in the first volume of the *Annalen der Sternwarte in Leiden*, published in 1868, was:

“The new observatory has been built midway between two wings, the first of which is the residence of the director, the other of the two observers and the two custodians, one of whom must be an instrument maker. A principal requirement is that this entire staff lives at the observatory, and that requirement has been met. The observatory itself contains spacious rooms for each of the instruments used, for the library, for the calculation rooms of the observers and calculators, a lecture room, and an instrument maker’s workshop.”

The government showed reluctance to include the item for the establishment of an observatory in the state budget. The politician Jonkheer Daniël Théodore Gevers van Endegeest now appealed to the Dutch people. Students and professors of Leiden University, as well as others, raised a considerable sum, enabling the founding of an observatory in Leiden. Only then, in 1856, was the item included in the state budget by the Minister of the Interior, Gerrit Simons. In 1861, under the direction of F. Kaiser, a new and larger observatory was built on a site that had been forcibly ceded by the Botanical Garden. At that time, the Observatory was situated on the outskirts of the city; there were no buildings along the Witte Singel yet.

In the previous observatory, only relative position determinations of celestial bodies could be performed. According to Kaiser's plan, the new one was also equipped to carry out so-called absolute independent determinations. The instrument for this was the meridian circle, a costly instrument. It was received on April 20, 1861, manufactured by the firm Pistor & Martins in Berlin, and was installed on the designated pillars within a few days. This telescope was located in Museum Boerhaave from 1955 until November 2024. The name Kaiserstraat , a street between Rapenburg and Witte Singel, still commemorates Kaiser.

The Observatory, located in an enclosed section of the Hortus, was an enclave within the city of Leiden. The building contained not only offices and domes with telescopes, but also residences for the professors and a few instrument makers, while several small houses stood on the grounds, inhabited by (single) assistants. The whole constituted a small, secluded community that remained intact until 1974, when the institute was relocated to a new building on the Wassenaarseweg, far from the city center. From that moment on, the Old Observatory became an annex of the Subfaculty of Biology. Biology was located on the Witte Singel in a block of flats with a tower and surrounding buildings on the grounds of the old Zoological Laboratory on Sterrenwachtlaan. The Observatory was used, among other things, as a specialized library, for party, lecture, and workspaces, and for its own minicomputer, a DEC PDP-11/45, as well as for punch card data entry for the central IBM S/370 mainframe.

The building was renovated from 2009 to 2011. Today, the building serves as a lecture hall for the Faculty of Law at Leiden University. Initially, it was intended solely for training and courses for professionals such as lawyers, but due to a shortage of space, classes are also regularly held in the building for law students. A visitor center has opened in the basement, accessible via the Hortus Botanicus. Guided tours are offered to the antique telescopes. In the latest spelling, an observatory is a stargazing station. The road from Kaiserstraat is therefore called Sterrenwachtlaan. However, the observatory is called the Oude Sterrewacht or simply Sterrewacht, in the classical spelling without an intervening 'n'.

 

<strong> More info: </strong>

50th National Stargazing Days from February 27 to March 1, 2026:

https://www.knvws.nl/evenement/landelijke-sterrenkijkdagen/

https://www.astronomie.nl/agenda/landelijke-sterrenkijkdagen-op-27-28-februari-en-1-maart-2026-731

Old Leiden Observatory, Sterrenwachtlaan 11, Leiden is open on March 1 from 14:00 – 22:00: https://werkgroepleidsesterrewacht.nl/