http://www.opentopia.com/images/cams/world_sunlight_map_rectangular.jpg

# This script loads a live view of the earth
# It can run as cronjob
DIR="/home/rw/bin/live_earth"

wget http://www.opentopia.com/images/cams/world_sunlight_map_rectangular.jpg -O $DIR/temp.jpg
temp=$(stat -c%s $DIR/temp.jpg)
if [[ $temp > 1000 ]]
	then
    rm -f $DIR/current_earth_wallpaper.jpg
		mv $DIR/temp.jpg $DIR/current_earth_wallpaper.jpg
fi

Nun noch ein Eintrag in die crontab:

PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
SHELL=/bin/bash
# m h  dom mon dow   command
*/5 *  *   *   *     /home/rw/bin/live_earth/live_earth_wallpaper.sh

# end

Alternative:

http://codefromthe70s.org/cgi/desktopearthgen.exe?width=3000&height=1200&height=1200&center=4&bars=0&clouds=1&utc=1254307130
center = 4 // noon, midnight, sunset, sundown, EUROPE/AFRIKA, America, Asia
bars = 0   // show black bars or not
utc = 1254307130 // timestamp for the map

http://codefromthe70s.org/desktopearth_gen.aspx