
Earth is the third planet from the Sun inside the Solar System, which is contained within the Milky Way galaxy. It is the home planet of the human species and acts as the main setting for most battles in the war between humankind and invading alien forces that take place throughout the course of the Contra series.
History
Throughout its history, Earth has suffered several invasion attempts carried on by alien forces, the third of which that was a full-scale war for the planet between humans and aliens, and which came to be known through history by the name of the "Alien Wars". As a result, most life on the planet was brought to the brink of extinction.
The planet has suffered several internal conflicts as well, which all in conjunction have culminated with the massive destruction of many of its cities and environments. Of note is a particular incident that took place in 2642 A.D. (six years after the Alien Wars), which involved the setting of a malfunctioning hyper-magnetic weapons grid during development that ended up eradicating 80% of Earth's population. Legendary Contra commando and Alien Wars hero, Bill Rizer, was unjustly blamed for this disaster, and was thus apprehended, judged and sentenced to be put into cryogenic sleep for 10,000 years. However, it was eventually revealed that he had just been the victim of a conspiracy meticulously planned by the Triumvirate –the highest authority of the Earth Federation Government– who were the ones held responsible for not only the Earth's internal conflicts, but also the ones who tried to hide the truth behind the numerous alien invasions of the past.
Many years later, at some point prior to 4444 A.D., the global population had completely abandoned the planet in search for new places where to live, which leaded to the establishment of many human colonies throughout the galaxy; all this with the hope to reestablish society someday.
When Earth became habitable once again, rather than returning to live in it, the entire planet was instead converted into a prison, home to criminals and political rebels. This eventually led to the rise of Neo Contra, which had plans to secretly destroy the many human colonies established outside of Earth rather than bring normal civilization back to the world.