For general astronomical information, see Solar System
Since the Fall, Earth and the rest of the Sol system has become paranoid. The 90 billion inhabitants of the Sol system believe that they are better than outsiders, and do not need to deal with them much. Most turn a blind eye to dealings for things in need, but believe that the government should either be ignoring those outside the system, or trying to rule over them.
These ideas are pushed on by the House of Sze Ma, the ancestors of the general who won the Final Battle of Earth, Sze Ma Rongji. The current head of the House is Sze Ma Tzu, Sol's Imperial President for Life and Decon of Earth and Luna. He rules fairly, and manipulates the news to say just that. While not as warlike as his famous ancestor was, he has a true thurst for power, but also a devious mind and a quick wit. This has allowed him to take the Celestial Throne of Luna from his cousins, and kept them away from power. The Imperial Solar Senate, formerly a democratically elected legislature and now an Presidentally-appointed bureaucracy, runs the day to day affairs of the government, led by Grand Vizer Shon.
The government of Sol is considered by most to be a Theocratic Monarchy, with the head of state also carrying a religious title. The House of Sze Ma runs the government, and holds most positions in the Imperial Senate while minor noble houses on other planets have minor say in the Senate and some control over the government. One of note is the House of Ares, a non-hereditary house which is based on Mars and can trace its membership and the ancestry of some members as far back as pre-First Federation. It is fully democratic in its actions, and as such holds little power off of Mars. It is also belived to be supporting underground non-worshipers or anti-worshipers (legal terms for non-religious and Heterodox people).
The government of Sol does not allow the sale or ownership of useable weapons. The only weapons available are collectors' items which have been decomissioned and are unusable. Some collectors find ways around this or recomission their items, but the penalty for this is no less than 5 years in prison and the siezure of all assests by the state. Constant survailence is carried out in all public places, and suspicion alone allows a thurough search of a person, their posetions or their property. Orthodoxy is the only religion allowed, and punishment for practicing anything else is no less than 5 years in prison and the siezure of all assests by the state if a relative or friend is not willed the items. If so, these people will have heavy background checks and possible interrogations to go through before getting such items.
The Military of Sol is larger than any military available, and is the most well trained and technologically advanced in the known galaxy. They still hold several Heavy Dreadnaughts, gigantic warships with large ammounts of power. Ships half this size haven't been built since before the fall, and these ships alone are more powerful than many planets' militaries. These ships, along with other capital ships, have been constantly upgraded to keep them from falling into disrepair. No capital ships larger than frigates have been built since the beginning of the Fall.
Half of Sol's military is not from its own forces, but mercenary companies. For the most part these companies, under the Sol Mercenary Authority, patrol the outer reaches of the system, fighting pirates and protecting the system. While the mercenaries are not as technologically advanced or have such big guns as the forces of Sol, they make up for that by actually fighting and testing their mettle, something the military of Sol hasn't done since they reunified Sol. Those who actually want to see action join the mercenaries, or the small detachments of Sol soldiers used to "punish" mercenaries who step out of line.