So the Overlords come to our solar system and, out of the goodness of their hearts, install a Dyson sphere for us overnight. They don’t mention exactly how massive it is, but it’s as big around as Earth’s orbit and it’s probably pretty massive. They mention in passing as they leave that they removed all of the planets out past Earth as part of the construction, but they did the job in a hurry and didn’t bother to clear out all the Earth-crossing comets or asteroids.
Still, not to worry: the sphere is made up of panels that can be shifted around to allow such bodies to pass through on the way in our out without hitting anything, so no Fists-of-God to mess up the nice landscaping.
But what happens to the comets and asteroids over the ‘long haul’ now? The Dyson sphere is massive, but when a comet is inside it, the sphere exerts no net gravitational force on the comet, so the comet’s motion is controlled by the Sun’s gravity. Outside the sphere, though, the comet feels the gravity of Sun + Sphere, so it’s orbit must get warped, right?
Is it possible to have a ‘stable’ cometary orbit under such conditions? It’s not a two-body problem anymore, so it wouldn’t be an ellipse, but maybe something like two ellipses bolted together? My gut says that the orbits would become quite chaotic and that no comet or asteroid would make more than one pass through the sphere before being ejected from the system or falling into the Sun.
What does the math say?