Krypton was, before its destruction, the home planet of the Kryptonian race, including Kal-El, the future Superman.
Planet Krypton
History[]
Krypton was the third planet from its sun Rao, located in the Ku'Raon System in the Xerius Galaxy. The Kryptonian race evolved on the planet until the point where their very bodies drew strength directly from Krypton's sun, giving them amazing abilities and nearly godlike in power. By the time Rao turned into a red supergiant, the Kryptonians lost their powers and Krypton succumbed to early ice ages. Because of these drastic environmental changes, Krypton's inhabitants developed advanced technology, enough to halt the tide of glacial ice. Because of their technological advances, the Kryptonians began to explore the farthest reaches of space and establishing a World-Gate network, allowing to explore much of the universe and contacting many alien races.
Kree-Skrull War[]
Due to their explorations, the Kryptonians founded themselves involved in the Kree-Skrull War. Immediately, both the Kree and Skrull Empires recognized that Kryptonian technology was infinitely superior to theirs. Both sides want them as allies, to completely annihilate the other. Initially, the Kryptonians tried to mediate for both sides to peacefully end their conflict but neither Kree nor Skrull would be satisfied until the other side was destroyed. Seeing there was no use in convincing either side to settling peace, every Kryptonian returned to Krypton and shut down the entire World-Gate network in order to prevent the Kree and the Skrulls from using it. Krypton underwent an isolationist policy from being involve in the Kree-Skrull War, but knew that the Kree and Skrulls would eventually come. In ensuring that their enemies would not come into the Xerius Galaxy, Krypton's brilliant scientists constructed a massive and heavily armed battlestation called Sentrius. The battlestation decimated millions of Kree and Skrull ships within minutes that forced the Skrull to abandoned the invasion while the Kree would persists for the next thousand years before finally leaving in defeat.
A period of peace resumed until the Shi'ar Empire under Emperor Kral'Nor expanded into the Xerius Galaxy. After the Kryptonians refused the Shi'ar from using the World-Gate network like the Kree and the Skrulls, and mediation deteriorated, the Kryptonians constructed a massive shield around Krypton to protecting the planet and constructing orbital defense weapons as it was then besieged by the Shi'ar for over five years. The siege ended when General Dru-Zod, the head of the Kryptonian Defense Force, and scientist Jor-El led a successful assault against the Shi'ar by utilizing the World-Gate network and Sentrius. The utter devastation of the Shi'ar forces resulted in Emperor Kral'Nor being overthrown by the newly established Shi'ar Republic, which in turn negotiated with Krypton for peace.
Following the end of the Shi'ar conflict, Krypton was left completely unguarded which allowed their long lost nemesis, the Dheronians, into teleporting a series of probes deep into the planet's core via Boom-Tube technology supplied by Darkseid, generating a force-field that prevented heat from dissipating to the surface and causing the planet to be unstable and on the verge of a catastrophic explosion. Only Jor-El foreseen the disaster from his geological surveys of the planet's subterranean layers, but the Council of Twelve found his conclusions outlandish, and considered the matter settled when Brainiac, an artificial intelligence with planet-wide oversight and control of Krypton, discounted Jor-El's findings. Unknown to the Council, Brainiac had secretly concurred with Jor-El, but had refrained from informing the Council so that it could successfully download its data into a satellite, rather than be tasked to organize an evacuation of the planet. In creating Brainiac, the Council had programmed it too well: the artificial intelligence considered the survival of Krypton's history and knowledge of ultimately more importance than that of its people.
Mere minutes before the planet exploded, Jor-El and his wife, Lara, launched their infant son, Kal-El, into space, bound for Earth. Kal-El would grow up to be known as Superman, one of Earth's greatest heroes. The explosion culminated in a chemical/geological reaction that imbued the remaining fragments of the planet with a specific radiation level that proved harmful and ultimately fatal to Kryptonians. Several of these fragments found their way to Earth, where they would be known as Kryptonite.
Kal-El's ship escapes Krypton's destruction
Aftermath of Destruction[]
Apart from Kal-El, the only known survivors of Krypton's destruction were the Kryptonian dog Krypto, who was lost in space in an experiment conducted by Jor-El, and General Zod, who was imprisoned in the Phantom Zone for war crimes against the Shi'ar during peacetime prior to the planet's destruction.
A more unfortunate legacy than Kal-El/Superman was Brainiac, which installed itself into an android body, in control of a massive warship, and traveled through the galaxy, "fulfilling" its programming by destroying countless worlds after absorbing their history into its library of knowledge.
The inhabitants of Argo had longed been died out because of a freak accident with the Eradicator, with the sole exception of Kara Zor-El. Several years after arriving on Earth, Superman and along with the X-Men traveled back to Krypton's solar system and found no remains of the planet except an asteroid belt of Kryptonite fragments. They followed a faint distress signal to Argo, and managed to revive Kara from cryonic stasis. However, they also discovered that the Shi'ar under the leadership of Kral'Nor's children D'Ken and Cal'syee were attempting to loot Kryptonian technology on Argo. The heroes, along with help from the Starjammers, forced the Shi'ar to leave the planet after reactivating Argo's latent Eradicator.
The truth of Krytpon's cause for its destruction would later came forth when the Dheronians attempted to eradicate the Kryptonian survivors on Earth, which the Dheronians were intent in destroying Earth in the same fate as Krypton's for harboring their hated species.