I like this, but I do see a couple problems. The diffuse glow on the horizon looks a bit fake. I like the clouds in the sky though. The planets/moons are pretty convincing, and generally pleasing to the eye. But aren't they just two of the same image, one shrunk down? That really jerks me out of the fantasy that I'm looking at a photograph taken on an alien world. Also, the planets are lit from their far side, and shaded on the side facing us. But the mountains seem to be lit from the side facing us. Since they must be lit by the same light source (one or more stars), they should be lit from the same angle. It sounds like a minor detail, but it makes a huge difference for how convincing to the eye your picture is!

Just to be clear, I really like this picture. I'm trying to give you constructive criticism because I'd love to see you make more stuff like this

Oh, and I think the mountains look good. It's kind of misty there, so maybe they don't need to be in crisp detail?

Thanks for the comment! really helps, indeed in think i should add more texture to the glow between mountains/sky

For the lighting yes i cheated , the light was originaly supposed to come behing the moutains as planets are lighted but then i though mountains where too dark so i lighted it up.

For the next image I will make i will take time to think about these details because its important to have something that makes sense since I am trying to get a realistic render ^^

So thank you very much for the critic its good

Awesome! I look forward to seeing your next work