I love the start of fall, and the start of spring, for plenty of reasons, but one fun astronomical reason especially.
The northern hemisphere tilts toward the sun in the summer, and away in the winter. That's why VP candidates and penguins have such long days in the summer, and such long nights in the winter.
But what's interesting to me are the Equinoxes. Think about it, the equator is pointing straight at the sun, so the whole world has essentially the same length of day. Billions of people, hundreds of countries, all kinds of different climates, and yet for a couple of days we all have a day and a night that is just about the same with equal parts day and night.
I don't have any moral to this story, I just think that's cool.