The James Webb Space Telescope has ruled out two of the strongest dyson spheres candidates after discovering that their infrared signatures came from distant background galaxies rather than alien megastructures, according to research published in July 2026 by the Project Hephaistos collaboration.
The two candidates, designated D and E, had survived increasingly rigorous tests as part of Project Hephaistos, a systematic search for technosignatures around red dwarf stars. Astronomers using JWST’s Mid-Infrared Instrument (MIRI) found that what appeared in earlier observations to be single stars with anomalous infrared excess were actually two separate sources: a nearby M-dwarf star and an infrared-bright galaxy positioned almost perfectly behind it from Earth’s perspective.
The problem began with the Wide-field Infrared Survey Explorer (WISE), which has relatively coarse angular resolution. “At the shortest wavelength you mostly see the star, and as you step out to 10 and then 15 microns the star fades away while a second source right next door lights up,” explained Olivia Curtis, an astrophysicist at Pennsylvania State University and co-author of the research. “The moment you see two sources where WISE saw one, you know the star was never the thing glowing.”
Candidate D harbored a Hot Dust-Obscured Galaxy, or Hot DOG, at a redshift of approximately 0.9, whose central supermassive black hole heats vast clouds of dust. Candidate E concealed a dusty starburst galaxy at redshift 0.4, where stars form at an exceptionally rapid rate. Both galaxies naturally produce the warm infrared glow that astronomers search for when hunting Dyson spheres—structures hypothetically built by advanced civilizations to harvest a star’s energy output.
Project Hephaistos initially identified seven M-dwarf candidates in 2024 after sifting through roughly five million stars using data from Gaia, 2MASS, and WISE. The team looked for stars exhibiting infrared excess—more mid-infrared light than ordinary stars should produce. Dyson spheres, if they exist, would emit waste heat as a signature, making them bright in infrared wavelengths.
The JWST findings demonstrate how easily background galaxies can impersonate alien megastructures. Candidate D passed every archival test available before JWST observations and emerged as the most promising Dyson sphere candidate on the board. Yet its hidden galaxy was offset by only about one arcsecond—roughly the apparent size of a coin viewed from three miles away. Candidate E proved even more deceptive: its background galaxy was an extended, clumpy system with the foreground star landing almost exactly on one of its brightest infrared knots.
What This Means for Future Searches
Rather than ending the search, the findings strengthen it. “Young fields grow up by hunting their false positives all the way to the ground, and every one of these teaches the next survey what to cut,” Curtis said. “We now know the most dangerous impostor in this game, a rare breed of dust-shrouded galaxy that hides in ordinary light and blazes in the mid-infrared.”
The research revealed two scientifically interesting galaxies that might otherwise have gone unnoticed. The star-galaxy alignments also provide a gift to the next generation of giant telescopes, which will be able to use the much closer star as an adaptive optics guide while observing the more distant galaxy in greater detail. The two-source geometry creates an opportunity to study distant galaxies with unprecedented precision.
The work establishes a rigorous methodology for vetting Dyson sphere candidates. Future surveys will inherit what Curtis called “the whole recipe”—a gauntlet running from all-sky surveys through radio imaging to JWST observations. Whatever survives such scrutiny next time will have earned genuine scientific attention as a potential technosignature.
Sources
- ScienceAlert — JWST observations of candidates D and E, background galaxy identifications, quotes from Olivia Curtis
- arXiv (Project Hephaistos – IV) — JWST/MIRI imaging and spectroscopy details, redshifts, galaxy classifications, observational methodology
- SETI Institute — Overview of Dyson sphere searches, infrared excess phenomena, background contamination issues
