Render a Starship Shield Impact - Blender 2.5 - page 50

3. Now let's see the setup for row B:

First we add a Render Layers ( Add → Input → Render Layers ) node, and pick the
Planet renderlayer; to create the image buffer for this renderlayer, let's click on the
camera icon in the botom right-hand side of the node. In this screenshot we can see
two processes being performed. The Blur and ColorRamp at the top are used to
create a glowing efect for the border of the planet; noice that the Blur node input
is not the image from the render layer, but its Alpha channel; the blurring creates a
sot region of transiion between the planet and the empty space around it, then the
ColorRamp takes that grayscale image and maps it into a gradient.

The color stops for the ColorRamp are as follows:
F Color stop 1:
Color: 0 Red, 0 Green, 0 Blue
Posiion: Completely to the let
Alpha: 0

4.