Dyson sphere



A Dyson sphere is a megastructure or a series of structures meant to completely encompass a star for the purposes of solar power, or to serve as a massive habitat. The concept was originally described by the physicist Freeman Dyson as a system of orbiting solar power satellites meant to capture a star's entire energy output. Dyson speculated that such structures would be the logical consequence of the long-term survival of technological civilizations, and proposed that searching for evidence of the existence of such structures might lead to the detection of advanced intelligent extraterrestrial life. A three meter thick Dyson Sphere with an Earth orbit radius would require an estimated 2.12057325 x 1023 cubic meters of material.

The Forerunners, being a Tier-1 civilization, were capable of building such constructs in various sizes, from full scale to miniaturized, planet-sized structures. One such structure was even moved into slipstream space where it would appear in a compressed form, far smaller than its actual size the physical universe. Dyson spheres were the basis for the Shield Worlds built by the Forerunners as safe havens from the Flood and the activation of the Halo Array. However, the Forerunners never made it to the safety of these installations due to the betrayal of the AI Mendicant Bias, whose defection to the Flood forced the Forerunners to abandon their plans. Basically, the structure fulfills its function as a "Shield World" perfectly. It protects the occupants of it and gives them a huge "world" to live in. Potentially, an entire new civilization could be constructed in a Dyson sphere.

Onyx
At the core of the artificial world Onyx was a slipspace rift that shunted those that passed through it to a structured Dyson sphere with an Earth-like, habitable inner surface. This construct is separated from a normal space-time symmetry by advanced Forerunner slipspace technology, making it only a few meters in diameter in real space despite being 300 million kilometers (or approximately two astronomical units [1 AU is 149,598,000 km]) in diameter on the inside. The Micro Dyson sphere is located in a factually compressed Slipstream space. In other terms, any object inside might appear to be a certain size, but inside the Slipstream bubble it is much, much larger. This led Dr. Catherine Halsey to dub it as a "Micro Dyson sphere". The Micro Dyson sphere's star has a spectra and energy output slightly smaller than the dimensions of Sol.

Flood-controlled Shield World
The Forerunners also constructed a Dyson sphere vastly different from the Onyx installation. Unlike the Micro Dyson sphere within Onyx, the construct inside this Shield World was a far smaller structure located in normal space, on the inner surface of an artificial planetary shell. Inside the shell was a network of ship-sized portals allowing access from an opening on the outside to the interior world.

The interior possessed an artificial sun, though it and the entire structure were on a far smaller scale; while the Dyson sphere within Onyx was millions of kilometers in diameter, the diameter of this structure was a mere few thousand kilometers. Unlike Onyx, it was seemingly not only designed as a bomb shelter, but also as some sort of harbor, shipyard, or hiding place for ships, as it contained the Apex site, which had dozens of Forerunner warships stored within it.

List of appearances

 * Halo Wars
 * Halo: Ghosts of Onyx