Ellipses are closed so the planets we see in elliptical orbits stick around. A circle is a special case of an ellipse and it is theoretically possible for an orbit to be circular. In the real world, a such an orbit is unlikely.
Ellipses are closed so the planets we see in elliptical orbits stick around. A circle is a special case of an ellipse and it is theoretically possible for an orbit to be circular. In the real world, a such an orbit is unlikely.