Here is an interesting duo of images to compare, but I'm at a loss to describe how or why they came to be this way. The top image is an inked and nearly finished comic cover by Gil Kane. It functions well as a cover ready for production—coloring, adding the issue #, price and DC logo. But it never went 'beyond' that stage (a pun that is stillborn) . . . but the bottom image is the same cover, rendered completely by Neal Adams, and made its way to the comic spinners where I bought it 42 years ago.
Okay, so why wasn't Kane's cover used, though you can see the title changed, and actually Neal Adam's cover is better because the angle of the comet earth is more acute, aiming right for our intrepid moon men, and the angle of the scene puts them in more imminent danger. Was Kane's rejected? But why not have him redraw it? A whole bunch of other meaningless questions come to mind, but all I know is—any answers might stagger the imagination and would come from . . . BEYOND the UNKNOWN!

Gil Kane — From Beyond

Neal Adams — From Beyond the Unknown #3 — 1970