“Astronomy for sailors”: a web game to learn physics using the stars and a clock

If you were on a boat in the middle of the sea how could you guess your position using just the stars and a clock? This is the challenge for hundreds of students at our interactive astronomy workshop in the context of the Genoa Science Festival held in Genoa (Italy) in 2021. Visitors played on the web application Astronomy for sailors which we developed from scratch. They could estimate their latitude and longitude in a virtual environment by measuring the altitude of the Sun above the horizon at solar noon and by using a marine chronometer. By recognising the brightest circumpolar constellations, they could learn how to find the North Star. The workshop included also an interdisciplinary section regarding orientation techniques in the animal world, ancient times and modernity. In this contribution we present the workshop's activities, highlighting their original and innovative aspects. We report on the positive feedback from students and teachers who actively played with celestial navigation during our workshop. Around 600 people have visited us and the web application Astronomy for sailors is still available online for free.