STEP 1
Open new document set the dimensions as you prefer.
Resolution set to 200.
Make fill black

STEP 2
Create new layer.
Open swatches and pick 50% gray.
Fill this new layer with the gray color.

STEP 3
To this layer of gray add noise. ( Filter > Noise > Add Noise )
Apply settings as shown.

STEP 4
Apply Gaussian Blur with setting as shown. ( Filter > Blur > Gaussian Blur)

STEP 5
Open levels adjustment
( CTRL + L on PC ) and bring the black slider towards the right and the white slider towards left. (see example)
You can play with this adjustment for the effect that you desire.

STEP 6
Create new layer. Choose star brush. Using various brush sizes and colors paint some more detail on new layer.

STEP 7
Open new layer. Fill with 50% gray. Apply Lens Flare filter ( Filter > Render > Lens Flare ) with settings shown below.

STEP 8
Set this layers blend mode to Hard Light. (the layer with lens flare)

STEP 9
Make 4 new layers. I filled the bottom of these with a green color (Blend mode Normal.) Next layer is filled with Cloud Filter (blend mode set to normal.) You can chose your on foreground and background colors. Fill the next layer with Render Cloud filter (once again the foreground/background colors are your choice.) Set this layers blend mode to Vivid Light. The 4th and top layer is filled with a light gray color Blend mode set to Soft Light.
Place these 4 layers into a group and set Blend mode to Linear Dodge (add.)

STEP 10
Create a new layer. Make sure the
Foreground/Background colors are set to black and white respectively. (Shift + “D”)
In this layer render clouds. (Filter > Render > Clouds) Apply a Hue/Saturation adjustment. (Image > Adjustments > Hue/Saturation) Make sure to tick colorize, you can play with these settings to your liking. Set this layer blend mode to screen.

STEP 11
Apply a Radial Blur Filter (set at zoom.)

STEP 12
Duplicate this layer and set the blend mode to Darken.

STEP 13
Merge the two layers. Apply a twirl distortion to this resulting layer twice.

STEP 14
Free transform (Ctrl + “t”) the layer and apply another Twirl distortion filter.

STEP 15
Use the eraser and free transform to get the desired look. Make some adjustments to the Hue/Saturation. (once again this is up to you as to the colorization and the scale/perspective)
Apply an Outer Glow FX. Set Blend Mode to Pin Light.

STEP 16
Duplicate the layer and apply a Surface Blur Filter. I used a layer mask to further enhance the shape I wanted on this layer.

STEP 17
On a separate layer use the brush tool to add some light in the center of the newly created galaxy. The colors and sizes of the brush is up to you. Apply an outer glow to this layer. Once again you can play with these colors and settings of the glow.

STEP 18
On another layer I added some more color with a soft round brush. Some smudge tool was used to create shape. Blend mode on this layer is Screen. Opacity set to 55%.

STEP 19
Make new layer. With soft round brush make another light, I chose white. Group these 5 layers together and leave the Blend Mode setting at Pass Through.

STEP 20
For the planet, Open a new document set dimensions to 1000 x 1000. Choose your foreground and background colors.

STEP 21
Render Cloud Filter.

STEP 22
Add noise filter, keep the amount low, I used 3%. Check Gaussian and monochromatic.

STEP 23
Open the channels tab. Make a new alpha channel. Click on new layer button.

STEP 24
Make sure your background/foreground colors are set to black and white and render clouds. Rename this alpha channel displacement.

STEP 25
Add a small amount of noise filter then fade the noise to around 50% (edit > fade noise)

STEP 26
Add difference cloud filter do this several times until the mix of white and black is about half and half. Make adjustments to the levels and brightness/contrast to bring up the black and white difference.

STEP 27
Go back to the layers pallet and duplicate the original cloud layer, rename the new layer highlights and turn the visibility of this layer off

STEP 28
Render a lighting effect to your original cloud layer. Apply the displacement channel to this as shown. You should play with the light settings to get them as you want.

STEP 29
Apply 3D > New shape From Layer > Sphere to both your layer 1 and the layer named highlights. Adjust the levels on the highlight layer and set the blend mode to Hard light.

STEP 30
Make a group from the two layers and copy them to the first document (your space scene) I used the brush tool to create a shadow on a layer beneath the planet.

STEP 31
The original planet was duplicated. The 2nd planet was scaled up with free transform and an outer glow FX applied. I also corrected its color use the Hue/Saturation image adjustment. The atmosphere is a layer of render clouds opacity adjusted.

STEP 32
For final adjustments I duplicated the saved image and played with the Shadow/Highlights adjustments then set this layers blend mode to overlay fill set to 52%. Then I added Curves and Levels adjustment layers.
CHECK THE LINK BELOW...Great tutorial about creating the stone material.

Thanks.