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

It’s a much more natural orbit. Although I’m sure there are planets out there with much more circular paths than we see in our solar system. But it basically works like this, any orbit that isn’t a perfect circle (impossible because of nature) is an ellipse. It’s also a more stable orbit, because if something pushed or pulled on something with a truly circular orbit, it would fall out of that orbit.

I believe Johannes Kepler discovered that previous were elliptical.