Why do planets move in an elliptical orbit instead of a circular orbit?

Question

And how exactly did we find out how they move?

In: Planetary Science

Answer 1

nothing in the universe is “perfect” including circles. if you look at the orbits of the planets next to a circle, you cant tell they arent circles. https://britastro.org/wp-content/uploads/2018/05/Figure-4_4.jpg

but for precision math, circles arent enough