Eli5, Why are planets orbits elliptical and not circular?

Question

Why, when the planet is accelerated during the ‘close phase’ of its orbit, isn’t it then flung away? I get that gravity pulls/holds it in orbit but why hasn’t it flattened out into a spherical orbit?

In: 5

Answer 1

All these closed orbits are equally valid. There’s no physical reason for eccentric orbits becoming naturally more circular. Eccentric orbits are fine.