Gravity – an elliptical orbit marks a perfectly round donut!

(Originally posted on Sunday, 14 June 2026)

Recently I was toying with an old Flash game titled The Orbit Game and I discovered that an elliptical orbit marks a perfectly round donut!



EDIT: I made another example, this time with planets of equal sizes, so it's easier to see where the barycenter is (in this case it's the place where the planets are touching each other). This time I also made the very first orbit much more elliptical, so it's completely clear that the barycenter is at one of the focus points of the ellipse right from the start.