Advanced Virtual Archaeoastronomy

The free and open source desktop planetarium Stellarium is a multi-platform astronomy program that runs on a wide range of computers, from powerful desktop PCs to energy-efficient single-board computers such as the Raspberry Pi 3 and 4. The volunteer develop­ers have finally reached their long-awaited "1.0" milestone, which marks both the com­pletion of accuracy goals for astronomical ephemeris computations and the adaptation of a major update to the underlying programming framework, preparing the program for further development in the coming years. Stellarium is a graphically detailed astronomy program that is popular with beginner to advanced amateur astronomers and astronomy teachers and students. It can immerse the observer in any location on Earth under the sky of any time in human history after 13,000 BC, surrounded by a landscape panorama that provides a reliable proxy for the real local landscape horizon. This allows the study of views from interesting human-made struc­tures or other locations in relation to features on the horizon and celestial phenomena such as solstitial or lunar extremes. The diurnal tracks for these events and several other objects, as well as some other interesting auxiliary lines, can be easily highlighted using a dedicated program extension (plugin). Another extension even allows a 3D architectural model to be loaded in its surrounding landscape (created from image-based modelling, laser scanning or architectural reconstruction) under the sky of the original period to dis­cover, investigate and demonstrate structural orientations towards astronomical targets and simulate light and shadow phenomena. Multi-phase reconstructions of landscape and architecture can also be visualised using the software's time control, which can control the visibility of model parts. In cases where the application requires interaction with the three-dimensional reconstruc­tions, such as astronomical observation instruments, Stellarium can be combined with a game engine such as Unity, which provides the necessary building blocks for computer game-like interaction with scene objects, while Stellarium provides the highly accurate sky background and astronomical time control. The latest developments include a new skylight model that provides a much more realistic simulation of twilight and detailed ephemerides for eclipses provided by new contributors. Stellarium is also capable of displaying constellations and star names from cultures around the world. This original feature has made it a popular tool for ethnoastronomy studies and outreach, and the Stellarium project welcomes qualified contributions from the community.