3. Superman’s worst fear was another creation of the radio program
In June, 1943 broadcast of The Adventures of Superman a new element of the Superman story entered the picture. The program, entitled The Meteor from Krypton, introduced kryptonite as capable of draining Superman’s powers. Kryptonite came from Superman’s home planet of Krypton. Initially, it was red, introduced in the comic pages in late 1949. Later it acquired the green color in which it is most widely associated. Eventually, many different colors and blends of colors of kryptonite appeared in the Superman saga, all of which had the power of weakening and harming natives of the planet Krypton. In the comic world, both Lex Luthor and Batman carry kryptonite, the former to oppose Superman, the latter to ensure Superman could be stopped if he ever went rogue and adopted evil.
The radio producers had a problem explaining how minerals from the planet Krypton could be found on Earth, at a time when space exploration was still mostly fantasy. They solved the problem by placing Krypton in the same solar system as Earth, exactly opposite each other in the same orbital plane around the sun. The destruction of Krypton allowed Earth to pass through the rubble during its own orbit, and the planet was showered with meteorites containing kryptonite. The solution created another problem. Superman supposedly derived many of his powers from the yellow sun, and Krypton had previously been described as having a red sun. Various plot devices were derived to resolve the discrepancy in both the comic pages and the radio adventures. Superman’s back story continued to evolve as his popularity soared.