Making a realistic night sky with the Adobe® Photoshop® software program can be as simple or complex as you'd like. You can add stars, a moon or even custom clouds, depending on your comfort level with using Photoshop's tools. You start with a gradient and add in stars using a special technique with the Noise filter, or hand paint them in. There are infinite creative variations on the type of night sky which can be created with Photoshop.
Create a new, blank file in Photoshop to get started. Do this by going to "File <New" and entering in your size parameters.
Add a new, blank layer in your "Layer" palette.
Fill the new layer with dark blue, dark purple or black. Do this by going to the menu: "Edit < Fill" and selecting a colour.
Apply a layer style to your chosen layer, and select "Gradient Overlay" from the drop down menu. Do this by going to the menu: Layer < Layer Style < Gradient Overlay." This will bring up the layer style dialogue box.
Select your gradient and change the colours to create the sky that you want.
First click on the tiny arrow which is displayed next to the default black and white gradient to display the other gradient options. Clicking on the actual gradient colour display brings up the colour boxes displayed beneath which allow you to choose the specific colours using the colour picker that you desire for your sky gradient.
Choosing blacks and dark shades of blue and purple work the best for this technique.
Click "OK" When you are done choosing the colours.
Add in Clouds. Create a new layer named "Clouds" and on this layer, select the menu: "Filter < Render < Clouds" which will create clouds using the foreground and background colours displayed in your tool bar colour picker.
Adjust the appearance of your clouds as needed. Do this by changing the colours in the foreground and background colour selector before applying Step 1. Change the opacity or layer blend mode on your cloud layer for different visual effects of the clouds displayed over your gradient sky. Mask out parts of clouds as needed to create a realistic scene.
Add in stars by first creating a new, blank layer labelled "Stars." Fill the star layer with black.
Apply the noise filter to the star layer. Do this by selecting the menu: "Filter < Noise < monochromatic." Apply Gaussian blur filter: "Filter< Blur < Gaussian Blur."
Adjust your stars by first, applying a levels adjustment to the stars until they appear to fade in. Apply a mask to the star layer to control where the stars appear in your sky. Finally, experiment with the layer blend effects of the star layer until it matches your night sky and you are satisfied with the image.
Using ellipse tool, create a white circle over top of your existing gradient sky layer.
Select the inside of the ellipse with the magic wand tool.
Render clouds onto the layer. Do this by going to the menu: "Filter < Render < Clouds" as you did earlier in Section 1.
Apply a distortion sphere effect to the clouds. Do this by going to the menu: "Filter < Distort <Spherize" and dragging the slider all the way to the right.
Adjust your layer blend mode by changing the blend mode from "Normal" to "Linear Light" which will allow the shadows of the moon to show through and create the illusion of a realistic moon in your scene.
Add a glow to your moon for extra dimension. Experiment with the layer blend modes for your star, clouds and moon layer for different visual effects.