Oils on particle board.
Cover for Jack Dann's The Man Who Melted,
published by HarperCollins Australia.
I had been carrying the idea around in my head for some time, and while flying over California one day, I gazed out the window and saw the sky I had imagined...only more perfect. Fortunately I had a camera in my hand luggage.
There are dozens of glazes to get the right glow of radiating light.