#4 - Stellarium

Stellarium is a stunning graphical app. Everyone's fascinated by amazing pictures of space like those shown by JPL, and Stellarium delivers in spades.

A rich set of menu options allow zooming in to planets or other celestial bodies and let any image to finely tweaked, increasing intensity or altering viewing position or proximity. A very interesting option allows you to watch the way a portion of space changes over time.

Stellarium's developers assert that this software really lets you see on your monitor precisely what you would see in the sky through a telescope, so precise are its calculations. That's hard for me to verify but the images it produces are absolutely gorgeous.

If you want to voyae into space without leaving your chair, or if you fancy a brilliant source of never-boring wallpaper images, Stellarium is a must.