Here is an interesting thing I noticed... Powers created TWO versions of the same painting for two separate editions of Wonder Stories. I never realized there were actually two different versions until I saw these issues side by side.
There is a 1957 edition (black text on gold banner at top), and a 1963 version (pink on purple text/banner). Although the same composition, these are obviously two different paintings. Why? Perhaps Powers could not locate the original art for the reprint 6 years later OR (most likely) he decided he could do a "better" job and decided to repaint it with improvements. In any case, these are both excellent in my opinion!