222 © 2021 EQUINOX PUBLISHING LTD an extended presentation of the open-source project Stellarium, which in the last few years has been enriched with capabilities for cultural astronomy research not found in similar, commercial alternatives. With this paper, we provide Georg Zotti et al. Cultural astronomers also value the possibilities they give of simulating the skies of past times or other cultures.

Modern incarnations are immensely versatile tools, mostly targeted towards the community of amateur astronomers and for knowledge transfer in transdisciplinary research.

However, in recent decades, 'desktop planetarium programs' running on personal computers have gained wide attention. The immer-sive sky simulator of the twentieth century, the optomechanical planetarium, provided new ways for representing and teaching about the sky, but the high construction and running costs meant that they have not become common.

For centuries, the rich nocturnal environment of the starry sky could be modelled only by analogue tools such as paper planispheres, atlases, globes and numerical tables.

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