If you are interested in astronomy, then you should visit the Ďáblice Observatory in Prague 8.
The Ďáblice Observatory was built on a rocky hill in Ládví in the 50's by an astronomical club which was part of the then-autonomous municipality of Ďáblice. It was opened for the general public in 1956 for the first time. The observatory is situated 325 m above sea level. The observatory building is comprised of western and eastern domes which are connected by a corridor, a lecture hall and a library. If the weather is nice, then you can see the Krkonoše and Krušné a Jizerské Mountains. If the sky is clear, you can also observe the sky with a telescope. Even if the sky isn't clear, you can watch astronautical films or see technical equipment in individual parts of the observatory.
There is also a permanent astronomical exhibition in the observatory where you can buy various publications and postcards related to various astronomical topics. In the mornings there are activities for children that include fairy tale readings and stories about astronomy.