Photoshop Tutorials


 * http://gallery.artofgregmartin.com/tuts_arts/making_a_planet.html
 * Planet tutorial.


 * http://www.solarvoyager.com/tutorials.asp
 * Various space graphic tutorials.


 * http://www.designshard.com/video-tutorials/space-and-planet-photoshop-tutorials-to-create-amazing-space-scenes/
 * Various space graphic tutorials.