Stellarium - Stellarium is a free open source planetarium for your computer.
SkyView - SkyView is powerful, easy-to-use app that answers questions about stars, constellations, and more.
Celestia - Real-time 3D visualization of space
SkEye - SkEye is an advanced Planetarium that can also be used as a PUSHTO guide for telescopes.
Star Chart - Stellarium is a planetarium software that shows exactly what you see when you look up at the stars. It's easy to use, and free. Read more about Star Chart.
KStars - KStars is a Desktop Planetarium for KDE.