working only with the original image posted, i noticed a LOT of noise in the picture. by resizing down to a smaller image it corrects almost all of this. i suspect this was a result of 'digital zoom' on the camera, which is basically nothing more than zooming in with a similar algorithm as photoshop. by resizing you get rid of that.
the next thing i did was clone out the dust in the sky and a few in a few other places. it really wasnt that much.
i then masked the sky and ran both a light median filter and a low gausian blur to even out the artifacting..
i also ran a histogram adjust to balance up the colors and brightness.
nice pic, btw
Craig