The Oort cloud, also known as the Öpik–Oort cloud, the Oort territories, or the Oort frontier, is a spherical cloud of comets and other possibly up to trillion icy objects that is thought to be the source for all long-period comets surrounding the Sol system. Astronomers believe it is way beyond orbits of the Kuiper belt. The Oort cloud is believed to be the source of long-period comets in the Solar System.
The Oort cloud may lie about 50,000 AU, or nearly a light-year, from the Sun. This means the cloud is nearly a quarter of the way to Proxima Centauri, the nearest star to the Sun. The outer limit of the Oort cloud defines the boundary of the Solar System and the region of the Sun's gravitational dominance.
The cloud is believed to be the home of dozens of independent or rogue spacecrafts orbiting around the sun. It is theorized that they sustain themselves through the capture of water-ice and helium objects to maintain their fusion reactors or through engagements of piracy of other space ships. It is not known how many are armed, as all ships usually avoids close contact.