Physicist Freeman Dyson's alien megastructure legacy

In 1960 during the early days of the search for extraterrestrial intelligence, theoretical physicist Freeman Dyson, who died last month, wrote an article titled "Search for Artificial Stellar Sources of Infrared Radiation" for the journal Science. He posited that "if extraterrestrial intelligent beings exist and have reached a high level of technical development, one by-product of their energy metabolism is likely to be the large-scale conversion of starlight into far-infrared radiation." One way to achieve that, he suggested, was by building an "artificial biosphere surrounding one star." And with that seed, the science fiction (science fact?) idea of an alien megastructure has grown, even making its way onto an episode of Star Trek: The Next Generation. From Elizabeth Howell's article in Space.com:

One of Dyson's daughters sent the physicist a videotape of a 1987 episode of "Star Trek: The Next Generation" called "Relics," Dyson said. The plot follows a distress call heard by the famous USS Enterprise starship; fans of the series may recall this as a crossover episode with "Star Trek: The Original Series" star Montgomery "Scotty" Scott (played by James Doohan).

The crew warps in space to the source of the call and discovers an immense Dyson sphere which is indeed portrayed as a solid spherical object surrounding a star. If we were to place this sphere in our own solar system, it would be so large that it would extend almost as far as the orbit of Venus, according to "Star Trek" fan site Memory Alpha.