Earth (Aboodash56)

Earth is the third planet of the Sol solar system, home to the humans, Inhumans, Mutants, and a number of Asgardian immigrants. It is also one of the Nine Realms, a group of planetary bodies aligned by the cosmic nimbus Yggdrasil. The various races of the Nine Realms refer to Earth as "Midgard", while those living beyond the realms call it Terra.

Earth orbits around one single star, the Sun, and has only one permanent natural satellite, called the Moon.

World War II
The 1940's were a tumultuous time. Depression years and racial disharmony in Europe sparked World War II, pressing various factions into a technology race. While Nazi forces occupied much of Central Europe, HYDRA, now masquerading as a Nazi science detachment, were making gains in unconventional warfare. Their leader, Johann Schmidt, actually managed to procure the Tesseract, an Infinity Stone that the Asgardian king Odin left on Earth some time after the Frost Giant attack in Norway.

In the last days of World War II in the European Theatre, Steve Rogers, a U.S. soldier, known as Captain America due to being enhanced with the "Super-Soldier Serum", prevents a missile launch by Nazis, which are soon revealed to be shape-shifting extraterrestrials led by one taking the form of SS officer Herr Kleiser. The missile explosion, however, knocks Rogers out and he falls into the icy waters of the North Atlantic, presumed dead.

The Age of Heroes
The dawn of the superhero age might have looked like a brief spark to those who grew up reading the exploits of Captain America, but it was soon to flare into a far brighter flame. The secrets of Erskine's formula had baffled scientists for decades until Dr. Bruce Banner, a graduate from Culver University, explored a new direction and decided to volunteer to recreate the serum. Despite warnings against self-experimentation, Bruce tested the serum upon himself and mutated into a raging green beast that was later dubbed the "Hulk", and found himself being hunted by military operatives that sought to exploit the transformation for the army's weapons division. The Hulk, however, would prove to have the heart of a hero by stopping maddened soldier Emil Blonsky, who used a similar variation of Banner's formula to transform himself into a grotesque, Hulk-like creature that destroyed the Mount Morris Dam.

Trivia

 * Because of the numerous alternate universes of Marvel Comics, this Earth from the Ultimate Marvel Cinematic Universe is officially known as Earth-TRN191.
 * This Earth is the alternate reality of Earth-199999, the primary Marvel Cinematic Universe.