On the monthly 'Astropolis at night' viewing evening, every 4th Friday of the month from 7:00 PM to 11:30 PM, the emphasis is on practical astronomy. For example, one can go into the large observation dome to peer through our giant telescope and, on occasion, we also set up some mobile telescopes and binoculars outside. We always start, around 7:30 PM, with the 'Constellation of the month' lecture in the Lemaitre auditorium. This is how we teach visitors a prominent constellation. We discuss its mythological origin and explain what you can discover in it, with binoculars or a simple beginner's telescope. In short, regardless of the weather, you always learn something! Just feel like coming by and talking about astronomy and space travel in our atmospheric Astrocafé? Then this is of course also possible!