An idea originally proposed by Earth scientist Freeman Dyson, a Dyson sphere can be described as a gigantic, artificial structure designed to completely enclose a star in a hollow sphere some 200 million kilometers in diameter. If constructed to support life, the interior of the sphere could theoretically provide the surface area of literally hundreds of millions of planets. Long beleived to be mere fancy due to the extreme size and astronomical amount of raw materials required for construction, a real Dyson sphere was found near the Norphin colony by the USS Enterprise-D. Built around a G-class star, the sphere did indeed have a M-class atmosphere clinging to its inside surface. The shell was composed of carbon-neutronium and had an internal surface area of 1016 square kilometers. No inhabitants were found, and it was believed they were long gone due the star's bursting severe radiation ("Relics" [TNG]).
