I find I often take the blue sky for granted. Crazy but true given it is such a huge part of our visual beings. The sky blue is also a color that varies little, even with a rich sunset like this , that blue is undeniably blue! I had fun waiting about ten seconds for the airplane and vapor trail to get in a place of my liking. The sunset did it all on its own.
any and all
Is this a composite: No
Pentax, 1/125, f/9.5, 300mm ISO200; adjustments in LR for brightness and contrast and, as is often the case with a blue sky, some cloning out of the darned dust spots that become obvious!