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King, Emperor, Captain! Today, we put a spotlight on the leaders of space research!

Today we celebrate the birthdays of two astronomers: Fredrik Kaiser and Jacobus Cornelius Kapteyn. During their lifetimes, both have dedicated themselves to making new places where the Universe can be explored. Today, on their birthday, we share their wonder of the universe with you. This will be done with an extra open day full of fun activities.

From 10 a.m. to 1.30 p.m., various activities will be organised for children and their parents by the JWG (youth working group for astronomy) and L.A.D.'F. Kaiser' the student association for astronomers. Look through a telescope and let an astronomer tell you what you see.

Starting at 2 o'clock, the Leiden Observatory Workgroup will organise a symposium where 3 speakers, Vincent Icke, Rob van der Berg and P.C. van der Kruit will tell more about Kaiser and Kapteyn. Tickets are 4 euro per person and can be bought in advance. Tickets can also be purchased on the day itself but gone = gone! The symposium will be concluded with a drink.

See you then!

Location: Old Observatory, Sterrewachtlaan 11 2311 GP Leiden


The children's activities are from 10.00 - 13.30 hrs.
The astronomers Q&A is from 10.00 - 13.30 hrs.
The guided tours start at 10.00 and go until 13.30
The symposium is from 14.00 - 18.15

Entrance: Free entrance for the children activities and the Q&A with the astronomers. In addition, the activities about the history of the Observatory will be free of charge. For access to the telescopes, a one-time fee of max. 4 euro pp must be paid. For the symposium also 4 euro has to be paid. Tickets for the symposium can be bought via this link.

The children's activities and the symposium are in Dutch. But the other activities are both in Dutch and English.