Stellarium is an open-source planetarium in 3D, available for the three main operating systems, where you can observe the night sky as though you were looking through a telescope.
Stellarium brings astronomer-level features to stargazers of all levels of interest. It’s not quite as robust as its competitors, but it’s also a much faster program.
With Stellarium, you will get access to over 600,000 stars, a realistic Milky Way, illustrations and asterisms of the constellations.
All things considered, Stellarium is without any doubt the best open source planetarium software for GNU/Linux platforms.
The fact of the matter is that it is actually the only one of its kind and does a very good.