Space Engine - Space Engine is a realistic virtual Universe you can explore on your computer.
Celestia - Real-time 3D visualization of space
WorldWide Telescope - The WorldWide Telescope (WWT) is a Web 2.
Stellarium - Stellarium is a free open source planetarium for your computer.
Cosmonium - Cosmonium is a 3D astronomy and space exploration program.
Solar Model - SourceForge presents the Solar Model project. Solar Model is an open source application.