1. Open a new Image 200x200px. Make a new layer and fill it with black.
2. Now go to filter>>render>>lens flare. Choose 105mm Prime and brightness to 100%.
It should look something like this:
3. Go to filter>>distort>>polar coordiantes and choose "Polar To Rectangular".
4. Go to image>>rotate canvas>>flip canvas vertical.
5. Go to filter>>distort>>polar coordiantes and choose "Rectangular To Polar" this time.
You can see a kind of orb already:
6. Select the "Elleptical Marquee Tool" hold shift and select the inside of your orb and cut it by pressing ctrl+X.
7. Open a new Image 200x200px and paste the orb (ctrl+V).
8. Now press ctrl+u and select colorize or press ctrl+b (i chose ctrl+b) and choose a color you want.
You can add a drop shadow like i did. Your done!!
More Tutorials: 
Absolutely lovely!