Locate the sun, compute the amount of sunlight going through your window.
Have you wondered where the sun will be?
With the position of the sun, you can
* Photography: find the best time taking your photograph.
* Travelling: avoid the strong sunlight.
* Curiosity: learn the sun's trajectory in the sky.
* Learning: For different parts of the world, see when the sun rise and set, and how high it is during the day.
** e.g. check out Greenland, Antarctica, or countries on the equator!
* ...
With "insolation", the amount of sunlight coming through a window, you can
* If you're finding a place to live, figure out what's the implication of the window facing.
* Understand why your room is warmer/cooler at certain times of a day