Stellarium is a realistic looking, feature rich OpenSource planetarium. The default catalog has over one half million stars, but you can get an extended catalog with over 200 million stars. All the usual information you expect in a planetarium is available. For the most part, navigation of the image can be done easily with a mouse or using the keyboard. The software takes over the GUI (like some games do). It can project (via a projector, I assume) for use in an actual planetarium or be used on your computer screen. You can get plugins for artificial satellite tracks and to interface with your telescope (or at least, work with your telescope).
The web site is here
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The web site is here
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