The atmospheric lighting will add on to the current lighting. It adds up as you step through space. You'll probably get better results just lowering the atmosphere color value to make it darker in the atmosphere node, or by setting the density to a lower number. You can also plug a 3D texture (like turbulence) in to the color input of the atmosphere node. This helps a lot. Scale up the turbulence to scales of 8 looks pretty good. Currently, all lights in the scene will add in to atmosphere, so too many lights will quickly blow out the scene. You can adjust rendering time of atmosphere by taking larger steps through the space (stepsize). If step sizes get too large, you'll start seeing banding. Then you can add noise to it (1 or 2) to make that better. This can speed up atmosphere. But, in general, for many renders, the atmosphere computes relatively quickly (for what it's doing). Larry