This is a painting by Norman Saunders used on the cover of Marvel Science Stories for April-May 1939.
I found both the painting and the cover at Pulp Covers, where the curators have also generously made the entire issue available for download. The ISFDB entry for the issue is here.
This is Marvel Science Stories for November 1950, cover by Norman Saunders. The ISFDB entry for this issue is here. I found this version of the cover at Pulp Covers, where the curators also include some interior art, including this piece by Frank R. Paul illustrating Lloyd Arthur Eschback’s “Overlord of Earth.”
And this rather dynamic illustration by Vincent Napoli illustrating A Bertram Chandler’s “Fire Brand!”
You can download and read the entire issue at the Internet Archive.
This is Marvel Science Stories for August 1938, cover by Norman Saunders. The ISFDB entry is here. I found this version of the cover at New Image: “Allegory of Censorship”