Update app.py

app.py

@@ -39,6 +39,7 @@ def add_planet(name, radius, mass, distance_from_sun):
     planet.animation_data_create()
     planet.animation_data.action = bpy.data.actions.new(name="OrbitAction")
     start_frame = 1
+    duration=2
     end_frame = int(duration * 10)
     for frame in range(start_frame, end_frame + 1):
         ##angle = (frame / end_frame) * 2 * math.pi