Hell yeah, a planet tutorial. I'm not going to unveil all my little secrets and tricks, for that's not the aim. The aim is for me to push you in the right direction and give you solid foundations for your work. Experimentation is the master key, you'll be spending an hour on that little detail in the texture, so get ready for a long sit on your chair (which I hope is comfy). Before I start the tutorial itself and before you start your masterpiece, remember that you are nearly always creating something fictious. But that doesn't mean you have to forget about physics and all. For example, you can't have two planets next to each other and such. Remember also that creating a piece is more than just technique. You have to think about the composition, the lines that guide you through the image. Each star must have it's own meaning, story. We're not talking about a few dots here, we're talking about thousand and millions of incandescent gas balls of different intensity, diameter and distance, ready to explose and die(you have to get all heated up about this). Now that you're all ready and cool, let's go.

What you'll be needing

• Photoshop.
  
• A camera, if you ain't too lazy.
  

Where do you start?

Well, first things first, we'll analyse what you need for a planet. You need:

• A base layer
  
• An atmosphere
  
• Texture
  
• Shadow Layer
  

See, easy huh? When you're working with planets, try to give your layers names and putting them in Layer Sets. When I start my Layer palette looks like this:


Rightie oh. Now you need your texture. I usually work with the biggest images I can get. Then I just select what I want and scale it.

Here's my base texture
Note: Mayang.com is great for textures ;)
Your camera comes in here, I usually go in my garden and shoot, but this is a tut, I just want to show ya ;)
As you can see, the image is 2560x1920 pixels. So I create a 3000x3000 canvas, paste my texture on it, desaturate it and duplicate it to fill the canvas.
Note: Duplicating can be done with the lasso tool, feather of about 10 - 20 pixels and then creating a selection, CTRL + ALT + CLICK on it to duplicate it.

Note: Scaled Version
Here's my second texture
Ok, now to spice things up, I'll take another texture and paste it over. I'll then change the blend mode to Linear Light
Note: Linear Light is just one possibility, try every blending mode.

Looking better already. Too add even more detail, create a new layer, render clouds (Filter > Render > Clouds), and then go to Filter > Sketch > Plaster and enter:

• Image Balance: 20
  
• Smoothness: 2
  
• Light: Top
  

Hit ok. Set the blend mode to Multiply and opacity to 50%. Tada, what even might look a bit like continents. W00T!
Now, continue on adding layer upon layer of textures. Go berserk.
Ok, the texture I'm going to use is this:

I highly advise you to spend some time on this step, tis very important!

Now, I'll create a canvas on which I'll put my planet. I use 500x500. Now, i'll create my Base, Atmosphere and Shadow layers.
Using the elliptical marquee tool and, holding shift to constrain the proportions, I'll create a perfect circle on my canvas. On the base layer, fill it with your principal planet colour. Then fill the atmosphere and shadow layers with black. Put the atmosphere blend mode to Screen. Now, put an outer glow, inner glow and inner shadow to your layer. Mine's set up like this:
Outer Glow:

Inner Glow:

Inner Shadow:

Note: These are values which are applying for my planet. The colour and size change from a piece to another.
So now I have this:


Ok, I hope you haven't closed your texture! Get to the texture, get your elliptical marquee tool, and create a perfect circle (hold shift to constrain proportions). Create it nice and big, the bigger the better. Merge your image and now, go to Filter > Distort > Spherize. Enter 100%. Then hit CTRL + ALT + F to reapply the filter with the window. Enter 50%.
Note: You can go for 100% twice, depends on how spherical your planet needs to be
Now drag this selection (if you're still in selection mode CTRL + CLICK + DRAG). Scale it down to your planet size and put it between the shadow and atmosphere layer. Now put the blend mode to Overlay, Hard Light or Soft Light. Play around and find the one you like the most. With Screen, I have this:

Now basically you're depending on your wits. Duplicate the texture layer and change the blend mode. Do that 6-7 times till you're nice and happy. I've got this:

Note: I changed outer glow colour to match

So that's good, but now that's not enough. So take one of the layers and bring up the Hue/Saturation dialog box and colour it. Then, create a new layer, render clouds and CTRL + CLICK on one of the Atmosphere/Base/Texture/Shadow layers. Then hit CTRL + SHIFT + I to invert the selection. Hit delete on the clouds layer. Now colour up those clouds and change the blend mode. A lot of fidlling here. Do this a few times. My planet:

Grab your shadow layer and apply a Filter > Blur > Gaussian Blur. On my 500x500 image I entered 50. Then, scale it and move it to chose your light source. I chose top right.

Wait - that's ok, but I have some atmosphere poking out. No sweat. Grab a big fuzzy brush and lightly erase on each layer the part you don't want.
Note: Keep an invisible copy of your base layer in case you want to load the selection of your planet.
With a bit of erasing:


Now you have a half decent planet, you can add some details to your piece such as stars and so on.

This was made only by experimenting. Trial and error is the best way for you to learn.

Next tut will be stars.
Thanks for reading to here :)
Examples of what was made with this technique:
Number 1
Number2