Download from PortableApps.com
Stellarium Portable can run from a cloud folder, external drive, or local folder without installing into Windows. It's even better with the PortableApps.com Platform for easy installs and automatic updates.
Stellarium Portable 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. You can view the planets and gaze at the stars in stunning detail. Stellarium includes vivid illustrations of the constellations and a theatrical display of ravishing nebulae and galaxies. With Stellarium Portable, you can transform any computer into a stargazing centerpiece.