Planetarium is described as 'A browser-based virtual planetarium of stars and planets customizable by location (latitude and longitude) and time of day' and is a Star Map in the education & reference category. There are more than 50 alternatives to Planetarium, not only websites but also apps for a variety of platforms, including iPhone, iPad, Android, Windows and Android Tablet apps. The best Planetarium alternative is Google Earth. It's not free, so if you're looking for a free alternative, you could try Google Earth or Stellarium. Other great sites and apps similar to Planetarium are Sky Map, KStars, Gaia Sky and NASA World Wind.