How to smooth color transitions

I stitched together a panorama of the city that I live in. The sky in the picture has an annoying dark spot, that I would like to smooth out without affecting the colors of the photo. Most online articles say to remove the sky and replace it with a gradient, but I would lose a lot of the detail that I want to keep (tower antennas, clouds, etc...) so I would like to smooth the color transition instead, and was wondering if anybody had some tips on how to do this? Thanks in advance, and here is a low res version of the picture.



--Daniel

PS. I was going for a halo affect on the city which worked out well, it is just that the harshness of the transition from bright to dark on the right side is too much.

Many ways to skin this cat,

A) Clone Stamp tool, clone one area to another (on a new layer)

B)Markee select the bad spot, add feather and then command or control "J" to past selection to a new layer (or go to "Layer/New/Layer via copy" then "Image/Levels" to britten the layer.

C)Use the "Dodge" tool to lighten the sky ( add a new solid gray layer with a blend mode of overlay, and dodge this layer to protect original pixels)

I could keep going but this should get the job done, always protect the original image, even if you just duplicate the original to modify