Stellarium

Stellarium 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.

* default catalogue of over 600,000 stars
* extra catalogues with more than 210 million stars
* asterisms and illustrations of the constellations
* constellations for eleven different cultures
* images of nebulae (full Messier catalogue)
* realistic Milky Way
* very realistic atmosphere, sunrise and sunset
* the planets and their satellites

interface

* a powerful zoom
* time control
* multilingual interface
* fisheye projection for planetarium domes
* spheric mirror projection for your own low-cost dome
* all new graphical interface and extensive keyboard control
* telescope control

visualisation

* equatorial and azimuthal grids
* star twinkling
* shooting stars
* eclipse simulation
* skinnable landscapes, now with spheric panorama projection