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

Planets move in elliptical orbits instead of circular ones because of how gravity works. Gravity pulls the planet toward the Sun, but since the planet is also moving sideways, it ends up in a curved path. This path is usually an ellipse because of the way gravity weakens with distance (inverse-square law) and because planets move faster when they’re closer to the Sun and slower when they’re farther away. So, the combination of the gravitational pull, the planet’s speed, and its distance from the Sun naturally leads to an elliptical orbit.