1. Create new document; RGB; 72 dpi; black background color.
2. Use Elliptical Marque Tool (M) select a circle of your choice.

4. Apply Spherize filter with default settings. (Filter-->Distort-->Spherize).

4. Now it's time to increase the expressiveness of texture. Do you remember? Well, Filter-->Render-->Lighting Effets.

Use Default Style, Omni, Red Texture Channel. Ok.