org.stellarium.Stellarium
Stellarium renders 3D photo-realistic skies in real time with OpenGL. It displays stars, constellations, planets and nebulae, and has many other features including multiple panoramic landscapes, fog, light pollution simulation and a built-in scripting engine.
Stellarium comes with a star catalogue of about 600 thousand stars and it is possible to download extra catalogues with up to 210 million stars.
Stellarium has multiple sky cultures - see the constellations from the traditions of Polynesian, Inuit, Navajo, Korean, Lakota, Egyptian and Chinese astronomers, as well as the traditional Western constellations.
It is also possible to visit other planets in the solar system - see what the sky looked like to the Apollo astronauts, or what the rings of Saturn looks like from Titan.
Latest reviews
Fantastic presentation of up-to-date astronomical data. Extremly useful for hobby astronomers. Track stars, satellites and other objects, useful to know where exactly they will be visible in the future. Even just if you are just interested in what you have seen in the sky, just fire up Stellarium and check it out.
The interface is terribly ugly, but the application itself is very cool and interesting. Flatpak works fine.
An amazing app to find the position of planets, stars etc. One of the most high quality OSS apps out there, glad it's on flatpak.