import vtk

source = vtk.vtkSphereSource()
source.SetRadius(1.0)
source.SetThetaResolution(32)
source.SetPhiResolution(32)

mapper = vtk.vtkPolyDataMapper()
mapper.SetInputConnection(source.GetOutputPort())

actor = vtk.vtkActor()
actor.SetMapper(mapper)

renderer = vtk.vtkRenderer()
renderer.AddActor(actor)
renderer.SetBackground(0.1, 0.2, 0.4)

window = vtk.vtkRenderWindow()
window.AddRenderer(renderer)
window.SetSize(800, 600)

interactor = vtk.vtkRenderWindowInteractor()
interactor.SetRenderWindow(window)

window.Render()
interactor.Start()