A Dyson Sphere is a hypothetical megastructure that completely encompasses a star and captures most or all of its power output.

"Although such megastructures may be theoretically possible, all plans to build a fixed-in-place Dyson

sphere are currently far beyond humanity's engineering capacity. However, parts of the technology,

like orbiting satellites and solar sails, have already been developed. Deployment of spacecraft and

satellites using photovoltaics might be seen as the first small steps towards building a Dyson swarm.

However, the number of craft required to obtain, transmit, and maintain a complete Dyson sphere far

exceeds present-day industrial capabilities. George Dvorsky has advocated use of self-replicating

robots to overcome this limitation in the relatively near term. Some have suggested that such habitats

could be built around white dwarfs[8] and even pulsars."