Why does Pi show up in so many diverse equations if it’s only related to a circle?

Question

Is Pi more than just a ratio for circles? Is there a easy way to understand the universality of Pi?

In: 1018

Answer 1

Easiest answer, given your own analogy… how many circles do you see in everyday life? Especially compared to straight lines?

I mean… the stars? The sun? Planets? Orbits? Even the grains of sand, and circles of the day itself. All of them… *described by Pi*.