Have We Really Detected Dyson Spheres?

Dr. Franck Marchis, a senior planetary astronomer and director of Citizen Science at the SETI Institute, and Dr. Lauren Sgro, outreach manager for LaserSETI and astronomer at the SETI Institute, discussed the possibility of Dyson spheres and recent research in a SETI Institute video. While no aliens have been found (yet!), Dr. Marchis explained that a Dyson Sphere is a hypothetical megastructure built around a star by aliens to harness energy.

Two papers published recently looked for signs of Dyson spheres by searching for infrared excess, which occurs when surrounding material absorbs light from a star and re-emits it as heat, causing astronomers to see more infrared light coming from a star than they would expect from the star itself. This could be evidence of alien technology, or something more natural. One project, called Project Hephaistos, found seven infrared excess candidates that were all M dwarfs (red dwarfs), the most common type of star in the universe. These candidates are relatively close to Earth (less than 1,000 light-years away), and their infrared light – many times brighter than expected – is compatible with the authors’ Dyson Sphere models. The second paper used a different methodology and search radius, finding 53 candidates with extreme infrared excess.

While exciting, infrared excess could also be caused by other phenomena, such as circumstellar disks (debris leftover from planetary formation, like our asteroid and Kuiper belts) or background objects like galaxies that emit infrared light.

More data from telescopes like the James Webb Space Telescope (JWST) is needed to solve the mystery. JWST could help identify artificial materials, confirm or rule out background galaxies, and provide more information about the candidates. The Allen Telescope Array (ATA) could also observe the stars and look for anomalous radio signals that might indicate an advanced civilization.

LaserSETI, another project in the search for extraterrestrial intelligence, is also being used to search for these candidates. LaserSETI looks for monochromatic laser light, which does not occur in nature, as a potential sign of advanced civilizations. LaserSETI stations are being built to cover the entire Northern sky and could detect those Dyson-sphere builders.

While it's too early to say for sure, the research is exciting and provides tantalizing clues in the search for extraterrestrial intelligence. Watch the video "Have We Really Detected Dyson Spheres? The Real Story" on the SETI Institute YouTube channel to learn more.