Xenon

The so called "twin world of [[Krypton]]," a far-distant planet -- evidently the moon of the planet Krypton until it "spun out of its orbit and left Krypton forever" -- which is smaller than Krypton in size but otherwise identical to it in virtually every respect. Xenon is the home of the scientist [[Zoll Orr]], who is a perfect look-alike for [[Superman]]'s father [[Jor-El]]. Zoll Orr is also the father of [[Kell Orr]], a young man who bears an uncanny resemblance to Superman. When Xenon is menaced by earthquakes and volcanic eruptions in February 1958, heralding the onset of a chain reaction within its uranium core identical to the one that once doomed Krypton, Superman courageously pits his powers against the wave of disasters and ultimately  devises a means of neutralizing the radioactivity at the planet’s core so that the potentially cataclysmic chain reaction can be halted and Xenon rescued from imminent destruction (S No. 119: “The Second Superman!” chs. 1-3-“The World That Was Krypton’s Twin”; “A Double for Superman”; “Superman’s Mightiest Quest”). (TGSB)