Krypton-II
Krypton-II. An artificially created duplicate of the planet Krypton, (along with it's own duplicate of Krypton's red sun), populated by android duplicates of the Kryptonian civilization as it was just prior to Krypton's destruction. It was to serve as a decoy for a malevolent fleet of alien ships that sought to invade Krypton.
The origins of Krypton-II came about as a result of several Kryptonian scientists learning of an alien invasion fleet approaching Krypton. Having no great defensive means of battling the malevolent alien armada, the great Kryptonian scientist, Jor-El, the father of Superman, devised the idea for Krypton-II. Creating a device known as an Atom-Scan Ray, Jor-El beamed a projection of a model of the planet Krypton into space, where flocks of meteors were suddenly drawn in from all over the galaxy toward the projection. Then, by remote control, the meteors were molded to form a duplicate of Krypton. An artificial red sun was then also created and placed near Krypton-II.
Having now created the planet, an android of virtually every person in Kryptonian civilization, and creature residing of the planet, was created - having been programmed to think and act like their original prototypes. (Among these android duplicates, there were duplicates of Jor-El, his wife Lara, their pet dog Krypto, the Kryptonian actress (and lost sweetheart of Superman) Lyla Lerrol, the Kryptonian film director Zik-Tul, and Kir-Du, the Kryptonian in charge of Krypton's Weather Control Tower). Since the androids did not need to breathe, they were transported to Krypton-II by means of a space barge.
Following the creation of Krypton-II, a large smokescreen was sprayed around the real planet Krypton, so as to hide it from the approaching alien armada and lure them to the decoy world. In the meantime, the androids on Krypton-II, as part of their programming, set about constructing a series of complicated booby-traps all over the artifical planet - all of which were set to go off should any aliens arrive on the planet. (Examples include the Kryptonian Fire-Fighting Robots programmed to attack various Kryptonian buildings and structures, Jor-El's laboratory was set to explode should anyone consider taking his 'secret files', and the Weather Control Tower was programmed to bring about a devastating shower of giant coloured hailstones).
However, just as the alien fleet approached Krypton-II, most of the ships were destroyed in space due to a "whirlpool of energy." In actuality, only a handful of alien craft ever landed on Krypton-II, and were then quickly destroyed having landed in a Vibrating Valley, that shook the ships to pieces, no doubt killing the occupants and rendering the craft unusuable.
Krypton-II was then left to drift on though space along with it's artifical red sun not long after this - having fulfilled it's purpose in saving Krypton. It does not appear, however, it's creators were conscious of the possibility of it colliding with a populated world, as over two decades after the destruction of Krypton, Krypton-II and it's red sun entered the solar system of Earth, threatening Superman's adopted homeworld.
As he flew out into space, Superman took note of the runaway planet's similarity to his destroyed homeworld. However, he was soon forced to land on it's surface due to the prescence of it's red sun, draining him of his powers. Realising it's resembelance to Krypton, an overwhelmed Superman came to believe his homeworld had somehow returned to existence. As he tried to investigate further, Superman inadvertedly set of many of Krypton-II's booby traps, bringing great destruction across the planet. Believing himself to be the cause of Krypton's second destruction, Superman, in a half-maddened and understandbly emotional state, vowed to perish on this world. However, shortly before the death of the android Lyla Lerrol, Superman had been given a microfilm projector.
The microfilm projector contained a recording of his father, Jor-El, detailing the creation of Krypton-II, and a later entry by the android Jor-El, telling of the arrival of the alien ships. Relieved that he had not brought about the mass-murder of his people and coming to his senses, Superman was then faced with the daunting task of how to prevent Krypton-II from destroying Earth, without the use of his powers. However, he quickly learned that the planet-wide destructive forces had knocked Krypton-II out of orbit, sending it hurtling into it's artifical red sun. Using one of the undamaged alien craft, Superman managed to work out of the controls and escaped the destruction of Krypton-II. Returning to Earth, his powers returned shortly afterward, but however, his experience of meeting the android Lyla Lerrol, caused Superman to miss his Kryptonian sweetheart all the more.(S No. 189, Aug 1966: "Krypton Lives Again!" "Krypton's Second Doom!")