OpenSpace - OpenSpace is open source interactive data visualization software designed to visualize the entire known universe and portray our ongoing efforts to investigate the cosmos.
Stellarium - Stellarium is a free open source planetarium for your computer.
Celestia - Real-time 3D visualization of space
KStars - KStars is a Desktop Planetarium for KDE.
WorldWide Telescope - The WorldWide Telescope (WWT) is a Web 2.
SkyView - SkyView is powerful, easy-to-use app that answers questions about stars, constellations, and more.