The reality of Earth-5391 differs vastly from many other realities. On this world it does not appear that there was an age of heroes. Many of the planets in Earth's solar system are also inhabited by alien species that are unique to this reality. It is also host to a number of unique planets and life forms as well. In particular, scientific advancement in the field of space exploration and related technologies had boomed in the late 20th century.
Unique races in Earth's solar system included Venusians, Martians, and Saturnians, the Birdmen of Uranus, the Core People of Earth, and an unnamed and unspecified four species. Earth's moon also supports life such as the Neganatives, Positpeople and Lunanimals. In addition this universe included other unique aliens elsewhere in the universe such as Blobs, the Starmen, the Half-Men of Haydes, An unnamed lizard species, Bems, Tigagators, Girafonkeys, Elepheagles, Jetmen, Mosquito Men, Ice People, Beastmen, Vegans, Scorpeople, and Centaurs among others.
The planet Earth also is uniquely different than most other worlds. The Earth is apparently hollow with another planetary mass within and a spatial void with planetoids. This is where the Core People reside. Other unique celestial masses include the planets Haydes, the Ghoul Planet, Denebola, Vega, Scorpio, and Sagittarius. Oddly enough many of these planets are referred to as "stars" or "constellations", when in reality they meet the classifications for a planet.
Space travel and other related technologies were commonplace in this universe. Earth and other planets in the solar system and beyond had rockets that could travel at great speeds and travel interplanetary or intergalactic distances. The most commonly used weapons were "Hydro-Rays" that fired rays of energy, presumably derived from hydrogen. Another primary mode of personal transportation was the Zoom-Vest, jetpack that strapped onto the back of an individual allowing them to travel short distances.
Not much is known of the history of this universe prior to the mid 21st Century. By the year 2075 the governments of the planet Earth is one of four worlds that is part of the United Planets which initially included Venus, Mars, and a third unidentified planet. One planet, Saturn, comprised of a warlike race of Saturnians, was not part of of the United Planets and sought to take over the solar system. The United Planets formed the Space Sentinels peace keeping force who dealt with various galactic threats as well as try to recruit other worlds into the United Planets.
The Commander of the Space Sentinels was Colonel Stone, among the many under his command were Captain Speed Carter, Lieutenant Crash Morgan, and Cadet Johnny Day. The Colonel's daughter Stellar Stone was in a romance with Speed Carter.
With Speed Carter, the Space Sentinels bravely kept the peace in the Universe. Carter can be credited with stopping an alliance with the Saturnians and the Blobs; shutting down Kop and his Starmen's attempts to steal a fleet of space ships; as well as stopping the Saturnians from infiltrating the United Planets and turning the robots of Earth against the population. Carter and his allies also stopped a renegade band of Birdmen of Uranus, inviting the Birdmen to join the United Planets. Speed also stopped mad scientist Professor Alfred Kurt from unleashing his Half-Men, and preventing an unnamed race of lizards from stealing Earth's sun, instead inviting them to move their asteroid world into Earth's solar system. Shortly thereafter the Space Sentinels stopped another Saturian plot involving a massive robot. They also stopped space pirates on the Ghoul Planet who used reanimated skeletons to rob planets, made peace with the Core People who lived below the Earth, staving off another Saturnian invasion with their help, and stopped the Bems from raiding other worlds. After discovering that the Neganatives and Positpeople of the Moon were at war with each other, Speed and his comrades helped broker peace by revealing their war was instigated by the Saturnians. They next stopped the Jetmen from destroying the Earth, imprisoned the Mosquito Men, stopped a renegade band of Ice People, put a stop to the Beastmen, and prevented a Vegan plot to attack the Earth. The Space Sentinels next stopped an asteroid of space pirates who were using mechanical Things to loot ships, prevented Comet and Bulka from infiltrating the Space Sentinels, and stopped the war between the Scorpeople and the Centaurs.
- Birdmen of Uranus
- Core People of Earth
- Half-Men of Haydes
- An unnamed lizard species
- Mosquito Men
- Ice People
- United Planets
- Space Sentinels
- Colonel Stone
- Captain Speed Carter
- Lieutenant Crash Morgan
- Cadet Johnny Day
- Stellar Stone
- Professor Alfred Kurt
- Characters from Earth-5391
- Other things related to Earth-5391
- Earth-5391's Appearances
- Media Earth-5391 was Mentioned in
- Images from Earth-5391
- Reality Gallery: Earth-5391