plz.how to remove the.....

[frank]

I have a photo rgb with the red ball and the vane,how do i do for replace the vane and the red ball to the same color of the sky?
i think there are tow solutions:
1 Do the copy-paste on the color picture and smooth the edge？
2 splite the picture to 3 grayscale picture and modifie these pictures to make a mask?
which one is feasible?or there are the other way to do this?
thanks for yours advises!