Dyson sphere

undated

A Dyson sphere is the name given to a hypothesised engineering structure built around a star and capturing a significant fraction of  its power output. The concept was first introduced by the science fiction writer, Olaf Stapledon and popularised by the physicist and mathematician, Freeman Dyson, who suggested that detecting such structures would constitute persuasive evidence of the existence of highly-advanced extra-terrestrial cultures.

I didn’t set out to make a picture of a Dyson sphere but, if they exist, they might look like this.