450 years of Leiden University: the Old Observatory
Leiden University was founded in 1575 and is the oldest university in the Netherlands. The university has seven faculties (six in Leiden and one in The Hague), with 33.701 students enrolled in 2025. Visitors to the Hortus Leiden can also visit the Old Observatory, featuring a temporary exhibition. This tenth blog covers: the Old Observatory.
The Old Observatory
Frederick Kaiser published a first design for an observatory in 1854 in the magazine *Lectuur voor de Huiskamer*. His plan was not carried out, 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 still commemorates Kaiser. Kaiserstraat, a street between the Rapenburg and the Witte Singel.
Exhibition in the Old Observatory
In Plants & Planets, you embark on a journey through time and space: from the Big Bang to the year 2125 and far beyond. Marvel at what science, art, and nature can tell us about the development of life on planet Earth. Discover biology and astronomy: from pollen to stardust, from plants to planets! From February 7, 2025, to December 24, 2029. In this presentation at the Old Observatory, you can marvel at what science, art, and nature tell us about the origin of life. What is the source of life? Where does organic growth come from? And what does that mean for us? Plants & Planets shows that scientists have made great leaps forward over the past century. You will be immersed in an all-encompassing experience: a journey through time and space. By the end, you might have even more questions than you do now. For exactly how life originates remains one of humanity's greatest mysteries.
The exhibition is open from Wednesday to Sunday from 11:00 AM to 4:00 PM. The exhibition is accompanied by an extensive program of activities including workshops, lectures, stargazing evenings, and guided tours of the domes of the Old Observatory. There are special children's sections and workshops for children. Admission to Plants & Planets is included with a Hortus ticket. An extensive review of this exhibition can be found in Mare, No. 23 of March 27, 2025.
https://www.mareonline.nl/archief/
Telescopes
Galileo Galilei (1564–1642) was an Italian physicist, astronomer, mathematician, and philosopher. He was a professor in Pisa (1589–1592) and Padua (1592–1610). Before Galileo used the telescope for his astronomical observations, he had demonstrated it to the Doge of Venice for military use around August 1609. Contrary to what is still often claimed, especially in Italy, Galileo did not invent the telescope: he introduced the Dutch viewer to the market. This early type of telescope was invented in Middelburg around 1608 by Lippershey or Sacharias Jansen.
Galileo improved the telescope in 1609. For a long time, it was thought that he was also the first to use the telescope for astronomical observations, but that honor goes to Thomas Harriot. It was a time when several scientists, full of anticipation, pointed their telescopes at the night sky: besides Galileo and Harriot, there were also William Lower, Simon Marius, Johannes Fabricius, Odo van Maelcote, Giovanni Paolo Lembo, and Christoph Scheiner. Galileo was the first to publish in March 1610. In *Sidereus nuncius*, in English *De Sterrenbode* (The Star Messenger), he described his observations. The moon was not perfectly smooth, as had always been claimed, but showed relief. Unlike Harriot, Galileo did not simply see spots, but realized, thanks to his artistic skill in chiaroscuro, that these were shadows. He had found the craters. Furthermore, he observed that the Milky Way was a collection of stars and that four bright moons orbited Jupiter: Io, Europa, Ganymede, and Callisto. He also observed the phases of the planet Venus.
A few months later, he pointed the telescope at Saturn and noticed “something” on both sides of the planet. He thought Saturn had two moons, but because he was not sure exactly what he had seen, he packaged his observation in an anagram. It was not until Christiaan Huygens in 1656 that concluded that what Galileo had seen must be a ring system. The craters on the moon and the sunspots, which he discovered later, contradicted Aristotle's teaching on the perfection of celestial objects. Galileo had a difference of opinion with the Jesuits from Zurich regarding who had discovered the sunspots first. That honor belongs to the Jesuits.
Van Gogh – De sterrennacht
From 1888, during his stay in Arles, in what is considered by many to be his most creative episode (February 1888 – May 1889), from which 187 works by his hand are known, Van Gogh painted various pieces resembling 'The Starry Night'. He himself called this period his 'Study of the Starry Sky'. For instance, in September 1888, he painted the piece 'Starry Night over the Rhône', which bears a strong resemblance to this painting. Vincent van Gogh created 'The Starry Night' in June 1889, when he was voluntarily admitted for an extended period to the Saint-Paul-de-Mausole hospital in Saint-Rémy-de-Provence for psychiatric treatment. He also made a number of pen drawings on the same subject. In mid-September, he sent the Starry Night paintings to his brother in Paris.
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