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Leiden Observatory Festival - Dive into the Universe

  • Leiden City of Science 2022
Sunday 25 September 2022
Oude Sterrewacht Leiden

As it does every fall, the Old Observatory opens all the way to the public! On 25 September, you can enjoy workshops and demonstrations all day long in the various rooms at the Old Observatory. You can take a tour of our historic telescopes, join workshops, or visit our More-than-Planet exhibit. Each room in the building has an astronomical theme and something to experience, from gravity to light and astrophotography.

Whether you are young or old, already know a lot about the universe or not, there is something for everyone to experience at the Old Observatory Festival!

The Leiden Observatory Festival is part of The Space Week, part of Leiden European City of Science 2022. Keep an eye on the website of The Space Week for all the activities there are to do.

How do I get a ticket?

The Leiden Observatory Festival is completely free! Just stop by and see what's on offer.

What is there to do?

Almost every room in the Old Observatory will have something to do during the festival, with each room having a theme. We will update this page whenever a new activity is added.

History: visit a telescope

The Old Observatory of Leiden not only houses some of the oldest, but also some of the largest telescopes in the Netherlands. During the festival, visit our telescopes with a guided tour by an astronomy student!

Climate change: More-than-Planet

Our planet is under a lot of pressure from climate change. In our visitor center we have an exhibition about the relationship between humans, technology and how we treat the earth: More-than-Planet. The exhibition is free to visit during the festival.

Light: experiment in the light lab

Light is really everywhere. Without realizing it, we use it all the time every day. But what exactly is light? And what kind of bizarre effects does it have? Find out that and more in the light lab of the Werkgroep Leidse Sterrewacht.

Astrophotography: capture the universe

On the evening of 25 September (weather permitting) the lights in the city will go out for Seeing Stars Leiden. For the first time in decades, the stars will come out in Leiden. The perfect moment to take beautiful pictures of the night sky! In this workshop you will learn all the tips and tricks of astrophotography, or taking pictures of astronomical objects. 


On the open day of the Observatory there are all kinds of special activities from guided tours to experiments with light, but sometimes something very simple can be fun. The JWG has provided a craft corner on open days for several years now, so that children can get to work with astronomy and space travel. This craft corner is also a must for the opening of Space Week!

Observing: scavenger hunt with the Huygens Telescope

We are L.A.D. 'F. Kaiser', the astronomical society of Leiden. We are a group of students with a passion for astronomy and the Old Observatory and can be found every year at the Old Observatory Festival in Leiden. This year, when the weather is good, you can find us in the backyard of the observatory where we will help people to operate the Huygens telescope. This is a telescope without a tube. It consists of 2 lenses and a piece of string! If you manage to use the telescope to find one of the objects that we have scattered through the garden of the Old Observatory, you might even get a small reward... In case of bad weather, we will organize an astronomical photo shoot. After all, nice pictures are a very important part of astronomy! We will provide the background and fun things to make your photo even more creative! So you only need to bring your creativity, enthusiasm and something to take pictures with. If your picture is Astronomy-worthy, you will of course receive a small reward!

Gravity: what keeps us together?

Gravity is omnipresent. It ensures that our feet are firmly planted on the Earth, that the Earth moves around the Sun and that billions of stars move through the Milky Way in a cosmic dance. But how does gravity actually work? And how do astronomers use gravity in their research into the universe? At the gravity workshop, you'll learn more about how gravity makes the planets move, as well as how astronomers can use gravity as a kind of lens.

Citizen Science: do science with us! 

When the lights go out in Leiden for Seeing Stars Leiden, we will notice how much light pollution there is in our city. How many more stars can we see when we remove that light pollution? We can map that together. This workshop will help you get started with the  'Loss of the Night' or 'Dark Sky Meter' app, with which YOU can do scientific research with us.

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