Free-Fall orbits are gravitational orbits where all planets start at rest and oscillate along open curves

(credit: @KangarooPhysics)pic.twitter.com/l8f1W7Lyqp

— 〈 Berger | Dillon 〉 (@InertialObservr) December 11, 2019

gravitational 3-body problems are great for chaotic dynamics. one of my favorites is the sitnikov system: given two equal massive bodies rotating about one another on ellipses, add a third tiny mass perfectly poised between them. give it a kick & what happens? pic.twitter.com/fn8ZSHF1kO

— prof-g (@robertghrist) December 8, 2019