You might wonder what meteor showers has to do with software...well there is a great open source app called Stellarium that can be used to locate stars, planets, constellations. It really is a great piece of software and worth checking out:
I love Stellarium. But my only wish was that I could use it as a screensaver.
I managed to solve that problem with one of the coding snacks I did (IdleStart
I created a shortcut to IdleStart and configured it to launch Stellarium.
I use 1200 as the first command line parameter (20 mins). Now it automatically launches after 20 mins of system idle time.
Just drop that shortcut in your Startup folder and you are all set.
Don't forget to turn off any real screensavers you may be using, in your desktop properties settings. (set it to use 'none')