constellations for 40+ different cultures.asterisms and illustrations of the constellations.extra catalogue with more than 1 million deep-sky objects.default catalogue of over 80,000 deep-sky objects.extra catalogues with more than 177 million stars.default catalogue of over 600,000 stars.Stellarium should appeal both to users who need something more academic and less distracting than Google or Microsoft's offerings, as well as those who have a need for an open-source planetarium. When you run the program for the first time it asks that you set your current location, but the mouse-over map of the world was too small to use easily. The nifty record feature is somewhat hampered by the dark interface. The controls live in the lower left corner and are transparent-a bit hard to find. Stellarium incorporates star-views from the Moon. Besides equatorial and azimuthal grids, users also get shooting stars when appropriate, eclipse simulation, and skinnable landscapes. They probably look better on a planetarium dome, which is why it's useful that Stellarium also includes a fish-eye view for curved surfaces. The dawn, dusk and atmosphere backgrounds were good, but not great on our monitor. There's a full Messier catalog of nebulae, too. The constellations of 10 different cultures are included, as well as illustrations and asterisms to help you visualize what the ancients saw.

The default catalog includes 600,000 stars, with upgrade modules that can push the count up to 210 million stars. It does run only in full screen mode, making any other programs you're running inaccessible except for the ALT-Tab switcher. It doesn't suck away your RAM into a black hole when loading or running. It's not quite as robust as its competitors, but it's also a much faster program.

Open source and currently in use by planetarium projectors, Stellarium brings astronomer-level features to stargazers of all levels of interest.