Install xphoon by entering the following commands in the terminal:
sudo apt update sudo apt install xphoon
Description:
sets the root window to a picture of the moon
xphoon sets the X root window to a picture of the moon in its current phase, including the partial lighting of the dark side by reflected earthlight. Picture is a monochrome dithered bitmap which is calculated via mathematical formulae. It keeps running on background updating the picture accordingly as time goes by.
Homepage: http://xphoon.sourceforge.net/
Version: 20000613+0-4
Section: universe/games