Your question made me wonder why the cycle would be a year long. I realized that's because when standing at 90 degrees north or south you're just rotating on th

Your question made me wonder why the cycle would be a year long. I realized that's because when standing at 90 degrees north or south you're just rotating on the spot. There's only the yearly day/night cycle because of the 23.5 degree tilt of the earth's axis, and this doesn't change relative to the plane of the orbit: https://www.youtube.com/watch?v=e9MU4TouzII&t=61 https://www.youtube.com/watch?v=e9MU4TouzII&t=61 This also explains why across 24 hours on the video in the blog the sun just "revolves" at the same height across the sky. In reality it's setting but it's imperceptible. At less than 90 degrees (anyone know the longitude?), the earth's rotation comes back into effect and the sun does go "behind the earth", i.e. it sets, daily, for a few months.