Looks realistic!
I´ll just mention some things that could improve it in my humble opinion, because I think it´s not much lacking to have a real winner.
In my opinion there could be more depth to it, although I know that it´s perfectly realistic for a planetary shot to look rather flat, just because the space we live in is not much more than the two-dimensional surface of a sphere, the atmosphere so thin.
But maybe you could enhance the depth impression a little bit, for example by adding different hues to the water close to the coast (I don´t know if you used a water shader, in my experience you don´t need it at this scale).
A really big breakup fractal and higher fuzzy-zone softness for the ice could also increase the impression.
I like the contrast in the right part of your polar cap very much!
One more thing I am wondering about is the lower hemisphere, no iceage there?
My best Regards,
J
