Thanks Joe. I've actually bookmarked Martin's tuts a few mins ago before your post ...need it for the glow.. and yup..i need to use the mask. I did start with a blank sky..and worked my way thru.. but yes..I agree..the niggling things have to be sorted out. Just re- rendered the trees and the snow.. so that the edges don't show..and will work on moving the galaxies to the back. 

You know what's killing me? That glow on the planet. I saw Martin's tut though.and it ought to work here. 

Like your The Discovery. Want to reach out and touch the planet. :-)

Fran..thanks. Most of it all was done in photoshop..will be working on it in the afternoon tmrow..(16 or so hours time..)  may I please do that and then tell you how i did it? Ought to be done around this time tmrow.  I didn't use hdri..am so damn scared of that lab..it's like I'll do anything to avoid it..(sigh..need to overcome my fear..). 

Most of what I did was screen and layer. The blue sky.. saturated and changed the hue till I got there.. stealing the colour from the original image. 

will put up the reworked image around this time tmrow.. or earlier..