I have always been fascinated by the properties of light. For years I have worked in places that did not have direct sunlight.
The basement from 1998 until 2012
The dark part of the floor from 2012 until 2015
A North facing window....scattered light from 2015 until 2019.
Now I am at a window with direct sunlight. Let the games begin!!
First I placed a glass crystal cube I received as an award in the window. Nice diffraction but not good enough.
So I bought a glass prism from Amazon.

Now I get a rainbow on the opposing wall I can use to tell the position of the sun and the approximate time. Plus it just looks nice.

Paul
PS The patching will continue until security improves