Mercury

Ah yes, Mercury, the plain Jane of the Solar System but also the most metal of the planets inside. The warm colour scheme looks good here and is what we expect when looking at an image of a planet that has a reputation of being one of the hottest. But to capture Mercury's tendency to get really cold on the night-side, maybe have the shadowed side here much less saturated (almost totally grey)as opposed to rich brown. Real Mercury is more grey-ish anyway but you'd only need to apply this to the night side to sell the notion to the viewer that this is a world that boils in the sun and freezes in the dark.

The yellow colour of the sunlight looks nice, but again - if realism is the goal it could probably be less saturated too as real sunlight in space is near-white, and the star here moreso gives me a "red dwarf" kind of impression. A blinding white sun might be visually jarring compared to the soft and serene mood set by the amber glow of a dimmer one, but blinding the viewer might actually be justified here, sine at the real mercury - the light and contrast would be very dynamic and a bit hard to look at.

The probe can stay as is - it's perfect <img src="e.deviantart.net/emoticons/s/s…" width="15" height="15" alt="" data-embed-type="emoticon" data-embed-id="391" title=" (Smile)"/>