It doesn't have the sun in it but Neo1 made a nice one using Terragen: http://www.renderosity.com/viewed.ez?galleryid=57542&Start=1&Sectionid=22&MostWanted=Yes

Description of lights in Image. 1 visible volumetric spot 1 visible volumetric abmbient inside a 85% transparent yellow sphere that is .1 larger than the ambient The (actual) sun is positioned at 330 - 25 to shed some light on the planet from an angle. This gives the gradient light effect on the surface. If the sun were positioned behind the planet, I get a black hole. I did try using just the sun as the light source over the planet but it tended to wash out the pic.

Check out Edit > Multi-Replicate (Alt-Shift-D) It allows you to choose the number of copies and their distance relative to each other (the last one placed). Just be carefull. The first time I used this I ended up with a 33MB file.