Program: Stellarium
Website: http://www.stellarium.org/
Grade: A
Cost: Free

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. This application is available for Mac OSX, Windows, and Linux. A useful guide is also available on the site that provides you with all of the information you need to get started. The imagery is amazing and very accurate. This is a very powerful tool that is being used in many planetariums. This is a perfect application for any class studying space.