Photoshop to vector
Asteroid Belt in Photoshop
by - Dean Tresadern 

im assuming you have basic knowledge of photoshop and know how to use it.

Things you need basic knowledge on
not much

Lets make some rocks :D

For this, we need a custom brush...make a new image 128x128 with transparent background draw a rock shape on the canvas

optionally, you can use a low opacity brush to paint a texture onto the shape
merge layers, select all (ctrl+A) and goto edit>define brush
make your new image and select your asteroid brush
goto the brush palette
goto [brush presets] i set my brush size to 16px size and then changed it to 8px later for smaller rocks

goto [brush tip shape] and set the spacing to what you want, i put it on maximum spacing

goto [shape dynamics] i set size jitter, roundness jitter, and angle jitter all the way up
goto [scattering] i set scattering all the way up, and count jitter all the way up

now you can either paint the asteroids around by yourself, or if your making an asteroid belt you can make a guide on a new layer, make a selection with the circle tool and do an inside stroke of about 8 pixels now use transform>scale to resize the circle into a ring and place it where you want your asteroid belt to be on another layer, use your asteroid brush and now follow the guide we just made around the ring several times until you have enough asteroids and thats basically it :)

Heres something extra you ca do to make it look a bit better.

Make a selection on your asteroid belt layer, and on a layer above fill it with R128 G128 B128 and goto layer style, add a bevel and point the light towards your lightsource
set the fill opacity to 0 and merge an empty layer onto it, make a selection and on a layer above that fill it with black use a large soft brush and delete away the bits where you want the light to shine through modify until it looks good, and you have yourself a fairly good asteroid belt heres one i made earlier! :D

this tutorial can also be used to made debris and shrapnel from explosions
PS: Tutorial written with the permission of the Author!
Dean Tresadern