Astronomers may have uncovered a promising new candidate for extraterrestrial life, right in our stellar neighbourhood. Using the James Webb Space Telescope (JWST), researchers have detected what appears to be a giant exoplanet orbiting Alpha Centauri A, the closest solar twin to our Sun. Located within the Alpha Centauri triple star system, this planet, tentatively named Alpha Centauri Ab, occupies the star's habitable zone, the optimal distance for liquid water to exist on its surface.
The discovery, made possible through direct imaging, marks a significant milestone in exoplanet science. If confirmed, this would be the first time such a potentially habitable planet has been identified around our nearest Sun-like neighbour.
Scientists believe that Alpha Centauri Ab's location in the "Goldilocks zone" could make it a prime target in the search for life beyond Earth. The finding also underscores JWST's unprecedented capabilities in spotting and studying distant worlds that were once invisible to astronomers.
"We found that in half of the possible orbits simulated, the planet moved too close to the star and wouldn't have been visible to Webb in both February and April 2025," said astrophysicist Aniket Sanghi of the California Institute of Technology.
Based on the brightness of the planet in the mid-infrared observations and the orbit simulations, researchers say it could be a gas giant approximately the mass of Saturn orbiting Alpha Centauri A in an elliptical path varying between one and two times the distance between the Sun and Earth.
"If confirmed, the potential planet seen in the Webb image of Alpha Centauri A would mark a new milestone for exoplanet imaging efforts," Sanghi says. "Of all the directly imaged planets, this would be the closest to its star seen so far. It's also the most similar in temperature and age to the giant planets in our solar system and nearest to our home, Earth," he says. "Its very existence in a system of two closely separated stars would challenge our understanding of how planets form, survive, and evolve in chaotic environments."
If confirmed by additional observations, the team's results could transform the future of exoplanet science.
"This would become a touchstone object for exoplanet science, with multiple opportunities for detailed characterisation by Webb and other observatories," said Charles Beichman of NASA's Jet Propulsion Laboratory and the NASA Exoplanet Science Institute at Caltech's IPAC astronomy centre, co-first author on the new papers.
