To make matters worse, the axis always points in the same direction.
I don't understand how this was never explained to me in high school. Of course we learned that the tilt of Earth is what causes seasons, but I never understood why. Now I know why I didn't understand it, some part was missing.
And I literally thought I wasn't smart enough to understand.
It follows from conservation of angular momentum :) If the axis direction changed (for a fixed orbit), then Earth's (or Solar system's, etc.) angular momentum would be changed, not be conserved.
Unless the Sun's tilt moved ever so slightly in compensation.
Around one one billionth of a degree to be exact. Impossible to detect.
Indeed. Another fact you can use is that in Newtonian mechanics (although not in GR due to frame dragging, only approximately), a rotating spherical body has the same gravitational field as a static one. So there would be no mechanism for the axially tilted rotating Earth to influence the Sun (different from a non-rotating Earth).
I guess a good animated 3d model, either digitally or one you can touch like this orrery, would have cleared up a lot of confusion. Especially if you can play with it in a darkened room with a flashlight.
Yeah, the critical insight is that the tilt impacts how high in the sky the sun is, which in turn affects the length of the day and the incidence angle of the sunlight.
They used to tell us you could stand an egg on its end on the equinox because the Earth was standing straight up and down. It really wasn't part of class, just something people mentioned. I even remember seeing a short news story of kids actually trying it in school. Then at one point one of my teachers pointed out people figured out you could do it any day of the year.
It does rotate, but it's slow enought to not matter in most cases. Afaik some ancient, star aligned constructions do not work anymore because of this
https://en.m.wikipedia.org/wiki/Axial_precession
The thing I spent some time puzzling about recently is why the changes to sunrise and sunset times through the year aren't symmetric about midday and why they have different rates at different time of the year. This led me to the equation of time [0], another fascinating rabbit hole.
[0] https://en.wikipedia.org/wiki/Equation_of_time
I noticed this often happens in school. A key piece of information is just missing and you just learn the right answer to pas tests, but never know why