Stellarium is a free virtual planetarium for your computer. Stellarium renders 3D photo-realistic skies in real time with OpenGL. It displays stars, constellations, planets, nebulae and others things like ground, landscape, atmosphere, etc. It is being used in planetarium projectors. It can also draw the constellations and simulate astronomical phenomena such as meteor showers, and solar or lunar eclipses.
Realistic simulation of the sky, sunrise and sunset
Default catalogue of over 600,000 stars
Downloadable additional catalogues for up to 210 million stars
Images of almost all Messier objects and the Milky Way
Artistic illustrations for all 88 modern constellations
More than a dozen different cultures with their constellations
Solar and lunar eclipse simulation
Stellarium is also used as an educational tool for teaching about the night sky. It works with Linux/Unix; Windows XP/Vista/7/8; 64-bit Mac OS X 10.6.8 or greater. A dark room is recommended for realistic rendering since details like the Milky Way or Star Twinkling can't be seen in a bright room.
Download Stellarium for Windows 32 Bit, Here
For Windows 64 Bit, Here