Why do planets orbit in ellipses?

1 Answer
Oct 1, 2017

They don't have to, it is just astonishingly unlikely that both foci of the ellipse will lie at the same point (one definition of a circle.)

Explanation:

Most celestial orbits are better described by ellipses than circles, but it took a genius like Kepler, and an astronomer with the skills of Brahé providing the data, to discover that.