I designed this star system banner after using the spherize tool in an online tutorial

The sun was made by making a flat texture use the clouds filter and emboss filters. Then the spherize filter was added and the outer edges were removed. To add the glow I used the feather tool

The planet were made in a similar way but the base cloud effect used a heavier emboss and a cloud flit with a decreased transparance was add to act as clouds. As I had so many planet to make I made a macro to created the effects.

The star background was made by using the noise filters