I discovered Bruce Pennington while searching through covers of "Stranger in a Strange Land." While not the original cover illustration, Pennington's is one of the most expressive covers. He had an excellent sense of color. In that same way that Giorgio de Chirico was able to achieve something surreal in "Mystery and Melancholy of a Street," Pennington is able to make his science fiction work seem dreamlike and strange.
Like de Chirico, Pennington's compositions are not always reliant upon anything out of place to attain his imagery. Rather, some of his images feel like an alternate reality, a reality seemingly very important in a science fiction tale, simply because of the color palette that he's chosen.
This seems particularly evident in the series of Ray Bradbury covers that he completed for Corgi publishing.
Pennington has led a very prolific life, producing works in the seventies all the way through the 2000s. He has since retired. His imagery and color palette seemed to change a little with the times, but I feel most drawn to his earlier works which seem so dependent on this surreal color palette.