Distant Suns
Very interesting stellar simulation program for amateur astronomers. One of its versions can be combined with the SETI@Home program, the well-known search for extraterrestrial life project.
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Cartes du Ciel
Excellent astronomical program created by Patrick Chevalley, with a fairly intuitive and configurable interface with detailed maps. You have the option to update the latest databases of anniversaries, comets, etc.
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Celestron The Sky
Program developed by Bisque Software generally for Celestron equipment. It is an interesting tool that constantly releases new versions. Includes databases from the Smithsonian observatory.
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Stellarium
Basic planetarium designed to show what the sky would look like from a location of your choice, on any date. Quite interesting and compatible with Windows, Linux and Mac systems.
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