Pretty good space art you made here! I really like the lighting on the planet, it's nice and subtly while still being crisp and sharp, especially the crescent on that planet.
Now what intriques me is the darkness and the starfield. There's almost no star and makes space look kinda flat and mainly empty. I think you should add some more stars and maybe a little bit of space gas that's very subtle to give it that nice, "out of this world" feeling. Also I think you wanted to make a strong contrast between the lighting and the darkness of the piece, but it's really hard to see anything else than the lighting on the planet. I suggest maybe turning down the opacity of the shadow layer that's on top of your planet to maybe 90%? A lot of people seem to do that and it kinda ruins the rest of the texture of the planet.
In my opinion, it's a really nice touch to add when you can slightly see a part of the texture in the night side of a planet so it makes you wonder what could be going on down there and if people live there and what it's like.