Starry Night - Professional astronomy telescope Control and planetarium software for Mac or PC
Stellarium - Stellarium is a free open source planetarium for Windows, Mac, and Linux
Eyes On - Experience Earth and our solar system, the universe and the spacecraft exploring them, with immersive apps for Mac, PC and mobile devices.
SpaceEngine - SpaceEngine is a realistic virtual Universe you can explore on your computer.
Celestia - Planetarium software.