As said above, I have seen so many beautiful planets, that the Earth and the Moon just pale in comparison.
#1 - The nebulae
I understand that we need nebulae for orientation in some systems. Whenever I reach the edge of an instance and there are just stars, I have no sense of movement or direction.
But there are so many objects around Earth (the sun, the moon, starbases) that orientation is not a problem at all. Also, the Vulcan and Andorian system have no or very little nebulae, too. I'd like to see something like that in Sol as well.
#2 - The sun
It seems that you wanted to show protuberance on the surface of the sun, but I think you overdid it a bit. Currently it looks more like a fuzzy hairball. I'd like less, but larger protuberance instead.
Also, the sun seems significantly darker in the center just like the stars in sector space.
(I'm not quite sure, but I don't remember a visible "main star" in the Vulcan and Andorian system. If they don't have one, they need it.)
Also, I think the nightside should be a bit darker to increase the contrast between the populated and the rural areas. Just an idea.
#4 - The Moon
I don't want to nitpick on every un-realistic detail (it's a game afterall), but I think the Moon is too small and too close to earth. (Sorry, forgot to take screenshots of the Moon).
I wouldn't care about any other system, but this is Earth. Earth. Our home. If the graphics should shine anywhere in the game, it's here. I hope you'll look into some suggestions and consider them for the other planets of the Sol system as well.