My original tumblr post was here. This image was first posted on tumblr by scificovers, which added the attribution “Amazing Stories, October 1947. Cover art by Robert Gibson Jones.” It comes to us via twofistedpulp. It traces back on the net to X-Ray Delta One.
If for some reason you wanted to *read* this story, it’s available from Armchair Fiction. Public domain print-on-demand stuff—very interesting for those of use who can’t lay their hands on the original issues.
http://www.sinistercinema.com/product.asp?specific=32469
Thanks for the link!