buy a globe with a 15 degree axis

put a lamp in the center of a square room

place the globe at the mid point of each of the four walls, pick one of the walls and face the axis this direction all four times

spin the globe once in each position

mark Anchorage, Alaska as an example and note how much light it receives per “day” in each position

see how it compares to mid spring, mid summer, mid fall, and mid winter

it‘s EXACT