Very good work, i particular like the antenna-horn and the eyes. The use of the mane as solar panels is both creative and fitting. The pose both fits Twilight and the rest of the picture and the details are very good, diverse and interesting to look at, but it does not seem overloaded. I like the shadowing on her, i can really imagine the sun on the left over my head, which leads me to some of the minor errors of this picture.
The planet in the background looks very interesting, but the raising sun over it does not fit the shadowing of Twilight. The terrain around Twilight could use some more clean lines, especially the rock she is standing on, also i think it would have been nice if the valley had one or two minor details in it.
All in all a very good work in two days and i am looking forward to a series of similar pictures for the rest of the mane six.