Set your desktop background to the astronomy image of the day. Grabs the daily astronomy image from http://apod.nasa.gov/apod/astropix.html and set's your desktop background to it. Graphically brings up an informative dialog when called with an argument (setspacebg 1).
Set the background image:
Display information about the background (download if needed):
(pacman package names)
hsetroot python-beautifulsoup4 libnotify wget youtube-dl mplayer vimeo-dl-git