I've already posted the scan showing A/S Superman creating a new Earth [Earth Q]:
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After re-reading that issue, I've come to the conclusion that "Earth Q" was possibly intended to be our Earth...
My reasoning..
Here, on "Earth Q", we see Friedrich Nietzsche (presumably) creating his famous Ubermensch, or "Superman" concept:
(You must read the panel very closely, to see the fine details.)
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Also, an unseen Joe Shuster (presumably), drawing the first modern Superman [as seen from Action Comics #1] on "Earth Q":
Just some food for thought. 🙂