Due to a request, the textures in this file are small (2000x1000) to lower the file size; you can get the original textures here. You can download the .blend with the fulsize textures packed into it here.
I have been working on this Earth for a while, It has a very nice Volumetric atmosphere, but it takes a while to render. If you want faster render times you can just exlude the layer with the volume atmosphere and add an atmosphere in the compositor. As is there is no compositing ( I love that it looks so awesome (at least I think it is awesome) without any compositing).
The textures are Nasa If you want to use this in something you will have to give credit to NASA, I don't care if you credit the author of the blend (me). I'm kinda confused by the licensing thing, I don't think you have to distibute works using this with the same license, you might want to look at NASA's website to make sure http://visibleearth.nasa.gov/useterms.php, I think you just have to credit NASA.
Many thanks to the Blenderartist Folks that helped me make the Volumetric Atmosphere!