From the December 2015 issue

Web Extra: In search of Dyson spheres

A half-century of advancements in the search for E.T.s has led scientists to find ways to track aliens who might not want to be found.
By | Published: December 28, 2015 | Last updated on May 18, 2023
Extraterrestrial signal
Once a civilization colonizes other planets in its home system, the inhabitants will need to stay in contact. Astronomers have started looking for pulsed-laser communications between worlds in systems where two planets align with each other and with Earth.
Astronomy: Roen Kelly
Astronomers have been hunting aliens for more than 50 years. In that time, detection methods have improved significantly, advancing from Frank Drake’s Project Ozma, all the way to modern attempts to find Dyson spheres —hypothetical machines built to surround a star and capture its energy.

How would astronomers know if they’d found such a monstrosity? It might look something like a strange star recently found using NASA’s Kepler telescope. KIC 8462852 dims in a way never before seen, however, astronomers still think it’s most likely surrounded by debris rather than alien megastructures.

Nonetheless, looking for Dyson spheres is appealing because the aliens don’t have to be trying to contact Earth the way most searches would require.

Science writer David Chandler described the quest in his story “The new search for alien intelligence.”

“If the aliens don’t drive themselves to extinction, the thinking goes, their civilization will keep expanding,” Chandler explained. “And any such society will have an insatiable appetite for energy. Ultimately, once the extraterrestrials have exhausted the energy resources of their home planet, they will take to space and start dismantling other planets and moons to build ever-larger solar arrays capable of capturing as much of the energy produced by the local sun as possible.”

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