SolCore

SolCore is the astrographic, cultural and political region encompassing the Sol system and its immediate surroundings within a five-light year radius. Officially, SolCore is one of the three primary categories of human colonies, the other two being the Inner and Outer Colonies. While SolCore formally includes the neighboring triple star system of Alpha Centauri and its colonies, in common usage the term most often applies to Sol alone. In both academic and colloquial use, "SolCore" also refers to the people (especially the political and/or commercial elite) of Sol, and can have variable connotations depending on the speaker.

History
The term has evolved and assumed many different meanings throughout history. Coined in the 24th century as humanity began expanding outward, SolCore had connotations to human unity and progress: as the collective trauma of the harrowing Interplanetary Wars faded to the historical background, the formerly contentious worlds of the Solar System all the way to the Oort Cloud and beyond were now seen as one political and cultural unit. Of course, this was an idealized version of a more complex reality, but the term caught on nonetheless, increasingly so as the Solar colonies began to conceptualize themselves in relation to the growing colonial sphere beyond the interstellar gulf. This was also partly spurred by the period of relative prosperity and advancement brought on by the Domus Diaspora. For a time, "SolCore" was near-synonymous with the United Earth Government, and remained so until the mid-25th century. Over time, the extrasolar colonies developed, the term began to assume more critical connotations, first within the academia in both the Inner and Outer Colonies: as the UEG's activities and centralized political structure drew increased criticism, so did the attribution of human achievements exclusively to the home system. Among many colonists, "SolCore" became a contemptuous term, highlighting the very shortcomings with the Earth government's attitude and even its political structure: despite attempts at reforms over the decades, the UEG's governmental bodies were still primarily staffed by SolCore natives due to their privileged position in the electoral process. Because of this, many Outer Colonials would apply it to the political-military sphere of the UEG and UNSC in order to highlight where said organizations' interests truly lie. Pressure from both colonists and the Earth public caused moderate UEG administrations to downplay the term in its original meaning, limiting its use to the astrographic and cultural region rather than the entirety of the UEG's dominion.

Culture and society
The colonies of SolCore are not culturally homogeneous, but centuries of concerted political, economic and cultural integration have tied their interests so closely together they are often seen as a singular unit, particularly by outsiders. Broadly speaking, the largest cultural groupings within SolCore are the Earthers, Lunars, Martians, Belters and Jovians, along with the colonists of Alpha Centauri's Proxima and Ammon. In addition, there are numerous smaller population groups, including the Cometarians, Communitals and other habitat-dwellers, as well as the populations on the moons of the Outer Planets and various minor worlds.

Production notes
"SolCore" was originally referenced in the before the release of Halo: Combat Evolved, appearing to be an early name for humanity's interstellar government and/or civilization. It is one of several pre-Halo concepts to be brought back and reinterpreted in Project Daybreak.