Article image

Hunting for 'Dyson spheres' across 1,000 galaxies to find alien life

The search for extraterrestrial intelligence is humanity’s grand quest. While we have yet to detect alien signals, researchers are exploring innovative approaches to this cosmic mystery. Project Hephaistos, a recent Swedish initiative, offers a fresh perspective by looking for astroengineering signatures such as Dyson spheres.

Unending quest for alien life

For over 60 years, scientists have scoured the skies for signs of intelligent life. Despite finding over 2,000 exoplanets, we haven’t detected any communication signals from alien civilizations. This raises the classic question: If intelligent life exists, why haven’t we found it?

One possible answer is that advanced civilizations might be exceedingly rare, even if planets are common. If technologically advanced civilizations are rare, we might be alone in our galaxy. Therefore, our chances of finding them improve if we extend our search beyond the Milky Way.

Expanding our search to include other galaxies could increase the likelihood of detecting signs of intelligent life. This broader approach allows scientists to explore a much larger sample of potential habitats for advanced civilizations.

Project Hephaistos

Named after the Greek god of blacksmiths, Project Hephaistos seeks signatures of extraterrestrial technology rather than direct signals. Funded by the Magnus Bergvall foundation and Nordenskjöldska Swedenborgsfonden, this project is the first Swedish initiative in the search for extraterrestrial intelligence.

Instead of focusing on communication signals, Project Hephaistos aims to detect signs of alien technology. This approach involves looking for large-scale engineering projects, interstellar propulsion mechanisms, and industrial pollution in the atmospheres of exoplanets.

By identifying these technological signatures, scientists hope to find evidence of advanced civilizations without relying on direct communication signals.

Civilizations utilizing Dyson spheres

The first paper from Project Hephaistos investigates more than 1,000 galaxies similar to the Milky Way. The goal? To find Kardashev type III civilizations that have harnessed their galaxy’s energy using technology like Dyson spheres.

Dyson spheres, proposed by physicist Freeman Dyson, are theoretical megastructures that could capture a star’s energy. These structures would encompass a star, capturing a significant portion of its output and indicating a highly advanced civilization. By examining data from these galaxies, researchers aim to identify unusual energy patterns or other indicators of such massive constructs.

The search revealed no strong candidates for Kardashev type III civilizations. However, it set an upper limit of 0.3% on the fraction of local disk galaxies that could host such civilizations. This means that less than one in 300 galaxies similar to the Milky Way may contain advanced civilizations utilizing Dyson sphere technology.

While no definitive evidence was found, this result still opens new research avenues within mainstream astronomy. The study’s methodology and findings provide a framework for future investigations and help refine the search criteria for detecting signs of advanced extraterrestrial civilizations.

Additionally, the project has uncovered several highly unusual galaxies that merit further study, potentially leading to new discoveries in astrophysics and the nature of galaxies.

Finding near-complete Dyson spheres

The second paper from Project Hephaistos focuses on detecting near-complete Dyson spheres using data from the Gaia space mission and the RAVE survey. Dyson spheres at this stage of completion would significantly dim the optical light from the stars they surround, creating noticeable discrepancies in distance measurements.

Gaia provides precise parallax measurements, which determine a star’s distance by observing its apparent movement against distant background stars. RAVE, on the other hand, uses spectrophotometric distances, which estimate distance based on the star’s brightness and spectrum.

By comparing these two distance measurements, researchers can identify stars with potential Dyson spheres, as a near-complete Dyson sphere would cause the star to appear dimmer than expected in optical wavelengths.

The researchers identified a handful of stars exhibiting the expected distance discrepancies indicative of near-complete Dyson spheres. These stars showed significant differences between their Gaia parallax distances and RAVE spectrophotometric distances, suggesting the presence of large structures dimming their light.

However, further observations suggested natural explanations for these discrepancies. One common issue is the presence of unseen companions, such as binary stars or planets, which can interfere with Gaia’s measurements and create the illusion of a distance discrepancy.

For instance, the star TYC-6111-1162-1 initially appeared to be a good Dyson sphere candidate due to its discrepant distances. But follow-up observations showed temporal changes in its radial velocity, indicating the presence of an unseen companion. This companion likely caused Gaia to misinterpret its parallax measurements, ruling out TYC-6111-1162-1 as a Dyson sphere candidate.

Upper limits on partial Dyson spheres

The third paper from Project Hephaistos explores the possibility of finding partial Dyson spheres by analyzing large astronomical catalogs.

The researchers scanned data from the Gaia mission, which provides precise measurements of star positions and distances, and combined it with infrared surveys such as the Wide-field Infrared Survey Explorer (WISE) and the Two Micron All Sky Survey (2MASS). These infrared surveys detect thermal emissions from objects, which are crucial for identifying potential Dyson spheres.

A partial Dyson sphere would not completely obscure the star but would still produce significant amounts of waste heat detectable in the mid-infrared spectrum. Thus, the researchers looked for objects with low optical brightness combined with high mid-infrared fluxes, characteristics that could indicate the presence of a partial Dyson sphere.

Despite many interlopers, primarily young stellar objects (YSOs) that can exhibit similar characteristics, the study successfully set conservative upper limits on the fraction of Milky Way stars that could host Dyson spheres.

Young stellar objects often produce excess infrared emission due to surrounding dust and gas, which can mimic the signatures of Dyson spheres. However, by carefully analyzing and excluding these interlopers, the researchers could focus on more plausible candidates.

The results were significant: fewer than 1 in 50,000 stars within 100 parsecs of Earth could host Dyson spheres that are 90% complete and operating at an effective temperature of 300 K. This limit provides a benchmark for the prevalence of advanced civilizations in our galaxy and helps refine future searches for extraterrestrial technologies.

Future prospects of Dyson sphere research

Project Hephaistos’s findings are promising. Two recent studies analyzed data from star-gazing satellites, developing methods to eliminate false positives in the search for Dyson spheres.

Ph.D. student Matías Suazo’s team at Uppsala University developed a pipeline to identify potential Dyson spheres. Starting with five million objects, they narrowed it down to seven compelling candidates. This structure would emit waste heat in the form of mid-infrared radiation that, in addition to the level of completion of the structure, would depend on its effective temperature.

Similarly, the International School for Advanced Studies in Italy found 53 star candidates with excess mid-infrared measurements. While natural explanations like debris disks remain plausible, the possibility of Dyson spheres can’t be ruled out yet.

The next steps

To confirm these findings, scientists need to take a closer look at the candidates, possibly with the James Webb Space Telescope. This powerful tool could provide the detailed data needed to distinguish between natural and artificial causes.

“It might be something that happens very rarely, like if two planets collide and produce an enormous amount of material,” emphasized David Hogg, co-author of one study. Regardless of the outcomes, the search for Dyson spheres and technosignatures continues to inspire curiosity and drive scientific discovery.

Explore Project Hephaistos’s papers on Dyson spheres, published in the Astrophysical Journal: Paper I, Paper II, and Paper III.


Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and


News coming your way
The biggest news about our planet delivered to you each day