Of course I have an idea I always do!
and this is the easiest way to achieve similar effect:
1) Get a silhouette you want to make glow. Preferably one that is rendered or you can render one of you know how.
2) Make sure you have enough background I used a black background on a separate layer under the silhouette.
3) Duplicate the silhoutte layer and put that layer on top. Hide it for the moment.
4) Give the original silhouette layer a nice outer glow fx. I used bight yellow here. (you can find fx by double clicking on the layer in the layers pallet)
5) Make a blank transparent layer between the black background layer and the silhouette. You can use any colors you like I used red orange and yellow here. Use a hard brush depending on size of pic (you can expirement) but I used one 5 pixels big here.just scribble a little with each color you choose on the layer directly around the silhouette. (I know this will look like silly but the next step will bring it all together)
6) On this layer go to Filter>Blur>Radial Blur Set it to Zoom Amount 89 and ok. Press Ctrl F to repeat this action.
7) Now make the top layer of the silhouette visable and just scribble a little around maybe the ears, tail some random edges with one of the colors and repeat step 6 on that layer. You are done.