Stellarium is a useful and free GPL software that renders realistic skies in real time with openGL. It is available for Linux/Unix, Windows and MacOSX. With Stellarium, you really see what you can see with your eyes, binoculars or a small telescope. Here are some key characteristics of Stellarium : · Over 120000 stars from the Hipparcos Catalogue with name and infos for the brightest ones. · Planets and major satellites in real time (position computation now accurate enough for eclipse or transit simulation). · Drawing of the 88 constellations with their names. · Mythological figures of the 88 constellations. · Textured displaying of more than 70 nebulas (Orion, M31 etc..). · Photo-realistic Milky Way. · Star twinkling. · Shooting Stars. · Skinable landscape (ground, fog, mapping of fisheye pictures). · Ultra fast realistic atmosphere rendering (Sunsets, sunrises etc...). · Automatic eye adaptation to sky luminance using physiologic model. · Grids in Equatorial and Azimuthal coordinates. · Equator and ecliptic coordinates lines. · Smooth real time intuitive navigation. · Powerfull zoom to see planet and nebula like in a telescope. · Equatorial and altazimutal mount mode. · Standard perspective and wide angle (fisheye) projections modes (e.g for planetarium dome). · Time control (real time and accelered time modes). · Graphical menu for simple utilisation. · Clikable stars, planets and nebulas with informations. · Windowed and fullscreen modes. · Full dome (180 °) projection mode for planetariums. · Text customer user interface for planetariums.