Stellarium for Linux is a free open-source planetarium for your computer. It shows a realistic sky in 3D, just like what you see with the naked eye, binoculars or a telescope. It is being used in planetarium projectors. Just set your coordinates and go.
What's new in version 0.12.1
Version 0.12.1 has added new features caldwell catalog for nebulae, re-packed star catalogs (Hipparcos and Tycho-2), delta-T manager, and star magnitude limit control.