Change the mode to Screen 100% and use a layer mask to reduce the effect at the top edges of the scene and on the planets:

Step 19

I used Levels to darken the effect:

Step 20

Place the nebula 1 image in the center of the sky and change the mode to Screen 100%:

Use a layer mask to remove the light on the middle and at the edge to get a subtle effect:

Duplicate this layer and use the Warp Tool (Edit > Transform >Warp) to bend this nebula image as shown below:

Use a layer mask to remove the hard edges and leave the effect visible only on the planet 2:

Step 21

Make two these layers selected and press Cmd/Ctrl+G to group them. Change this group mode from Pass Through (default group mode) to Screen 100%. Make a Hue/Saturation adjustment layer to change the color of the nebula 1:

On this layer mask I used a soft black brush to erase the middle as I didn't want it to be affected by this adjustment layer:

Step 22

I used Color Balance for this effect:

Step 23

I used Curves to make the effect more subtle and on this layer mask used a soft black brush to erase the sides as shown below:

Step 24

Place the model stock photo in the middle section of the ground and remove the background using a layer mask. Set this layer on the top.

To make her shadow, make a new layer under the model one. Hold down Cmd/Ctrl while clicking the model layer mask thumbnail to load its selection:

Fill this selection with black (Shift+F5) and convert it to a Smart Object. Flip it vertically (Edit > Transform > Flip Vertical) and lower the opacity to 50%. Move it under the model feet and transform it using Cmd/Ctrl+T:

Apply Gaussian Blur with 3px and use a layer mask to blur the top of the shadow a little:

Step 25

I used Hue/Saturation to reduce the model saturation:

Step 26

Make a Color Balance adjustment layer for the model:

Step 27

I used Curves to brighten the dark side of the model and on this layer mask erase the brighter side a little:

Step 28

Make a new layer on the top and use the Elliptical Marquee Tool (L) to make a selection of a circle above the mode (hold down the Shift key while drawing it):