Molly, that's wonderful! I used your fog idea and overlayed my globe with fog.
I used this image
for this world.
I scaled the NASA image by changing the height to 600 when I scaled it. Then I cropped the resulting image to 890 x 600 to make it a more manageable size.
Made a selection with the Rectangular selection tool in the brightest area of 450 x 450, Ctrl C to copy, Ctrl + Shift + V to make a new 450 x 450 image. Made it seamless and used Plastic Wrap on it. Then I used the Spinning Globe filter.
I sent ahead and used the NASA background I had resized, rotated and positioned the globe and cropped to the size I wanted. Combined the background, deleted the bottom layer.
File > New and the new image came out the same size as my globe image. Filters > Render > Fog (this filter is only available to those with Python) I used a turbulence of 1.5 so the fog wasn't too dense to see what was under it, and used a very pale gray for the color (f0f0f0), I didn't want stark white.
Made sure the bottom layer was selected in the finished globe image (it helps to zoom out to 25% and do Ctrl + E so that you have a much smaller image to work with). Activated the fog layer and in it's image window, dragged the top layer thumbnail over to the globe image and moved it down to the bottom layer. Filters > Animation > Overlay Background. Deleted the bottom layer, Then Optimized (Difference) the image.