1. Open up a new image document; the one in this tutorial is 300x300, transparent background, 72dpi, 8 bit. Foreground colour: black and Background colour: white
2. Go to Filter>>Render>>Clouds and then Filter>>Render>>Difference Clouds.
3. Next, go to Images>>Adjustments>>Invert and click it.
4. Click on Control + L to bring up the levels screen and move the center arrow over to the far right.
5. Next we're going to add some Radial Blur. (Filter>>Blur>>Radial Blur). Set the distribution to somewhere between 50 and 55, Zoom, Good.
6. Duplicate the layer by right clicking on it in the Layer Palette and selecting Duplicate Layer. Set the Layer Mode to Colour Dodge.
7. Now we're going to change the Colour Balance on your original Layer. First, click on Layer 1 in your Layer Palette to select it, then go to Images>>Adjustments>>Colour Balance and play with the settings until you get something you like.
8. Now we're going to thin out the brightness and give the flare a bit more of an explosive look. Select your Eraser from the Tool Bar and set the opacity to 50-60% then click on your Layer 1 copy to select it.
Use these Eraser settings:
Brush
Brush Diameter: 25
Hardness: 0
Opacity: 60%
Flow: 65%
Now selective erase on your Layer 1 Copy to get the explosive look (most of your erasing will be on the bright/midtones areas):
9. Now we'll smooth out our flare by brushing over Layer 1 with the Blur Tool.
10. Next we are going to add Lens Flare (Filter>>Render>>Lens Flare) to give it more of a celestial flare look. Center your Lens Flare in the middle of your Celestial Flare.
11. To make the Flare blend in better, add some Radial Blur with a setting of 40, Zoom, Good.
You can either leave the Celestial Flare as is, or you can play around with the Hue & Saturation to change the colours/tones of your flare. (Images>>Adjustments>>Hue/Saturation)
Layer 1 Setting I used for this tutorial:
Layer 1 Copy Setting I used for this tutorial:
I also went over Layer 1 with the Blur Tool once more for a final smoothing.
More Tutorials: 
