Using huge distances makes objects glitchy.
Since your camera is at Position.X 45252 and the planet is at Position.X -180000 you can bet that has something to do with it.
Also Roblox’s rendering makes items less detailed the farther away from the camera you get.
You could add a Mesh instance by pressing Ctrl + i combination and searching typing mesh. After the mesh is inserted, select it and set the MeshID value to the mesh ID of your sphere.
Now, you can also set the RenderFidelity property, and this is what will actually fix the issue for you.
Make sure the property is set to Precise, not automatic or performance. This will force the game to render the object at full quality regardless of the distance from the camera. You can read about it here.
This way you also don’t have two separate instances (the BasePart and Specialmesh) to represent your planets, and instead you only have one (Mesh).