"Astronomers
may have glimpsed the first compelling evidence of a giant planet
orbiting Alpha Centauri A, the closest Sun-like star to Earth—a finding
that, if confirmed, would mark a milestone in the search for nearby
worlds.
Just four light-years away, the Alpha Centauri system consists of three stars: the Sun-like pair Alpha Centauri A and B, and the distant red dwarf Proxima Centauri. While Proxima is already known to host several planets, repeated searches around Alpha Centauri A and B have come up empty for decades. New observations from the James Webb Space Telescope, however, suggest that may finally be changing.
Using Webb’s Mid-Infrared Instrument (MIRI), astronomers detected a faint source consistent with a gas giant orbiting Alpha Centauri A at roughly twice the Earth–Sun distance. Although the planet would lie within the star’s habitable zone, its inferred mass—likely comparable to Saturn—means it would not be a candidate for life. Its significance lies elsewhere: proximity. If verified, it would be the closest known exoplanet orbiting a Sun-like star.
Detecting such an object was technically formidable. Researchers used a coronagraph to block the intense glare of Alpha Centauri A, then carefully subtracted light from both stars in the binary system. What remained was a signal nearly 10,000 times fainter than the stars themselves. Earlier data from the European Southern Observatory, combined with detailed simulations, indicate that the planet’s orbit could remain stable despite the gravitational influence of Alpha Centauri B.
The candidate appeared clearly in Webb data from August 2024, but was absent in follow-up observations in early 2025. Rather than weakening the case, simulations suggest this pattern is expected: depending on the orbit, the planet would be hidden close to its star during roughly half of its path.
If confirmed, the object would become the nearest giant exoplanet available for direct study, offering an unprecedented opportunity to test theories of planet formation in tightly bound binary systems. It would also demonstrate that planets can survive—and perhaps thrive—even in gravitationally complex stellar neighborhoods."
Just four light-years away, the Alpha Centauri system consists of three stars: the Sun-like pair Alpha Centauri A and B, and the distant red dwarf Proxima Centauri. While Proxima is already known to host several planets, repeated searches around Alpha Centauri A and B have come up empty for decades. New observations from the James Webb Space Telescope, however, suggest that may finally be changing.
Using Webb’s Mid-Infrared Instrument (MIRI), astronomers detected a faint source consistent with a gas giant orbiting Alpha Centauri A at roughly twice the Earth–Sun distance. Although the planet would lie within the star’s habitable zone, its inferred mass—likely comparable to Saturn—means it would not be a candidate for life. Its significance lies elsewhere: proximity. If verified, it would be the closest known exoplanet orbiting a Sun-like star.
Detecting such an object was technically formidable. Researchers used a coronagraph to block the intense glare of Alpha Centauri A, then carefully subtracted light from both stars in the binary system. What remained was a signal nearly 10,000 times fainter than the stars themselves. Earlier data from the European Southern Observatory, combined with detailed simulations, indicate that the planet’s orbit could remain stable despite the gravitational influence of Alpha Centauri B.
The candidate appeared clearly in Webb data from August 2024, but was absent in follow-up observations in early 2025. Rather than weakening the case, simulations suggest this pattern is expected: depending on the orbit, the planet would be hidden close to its star during roughly half of its path.
If confirmed, the object would become the nearest giant exoplanet available for direct study, offering an unprecedented opportunity to test theories of planet formation in tightly bound binary systems. It would also demonstrate that planets can survive—and perhaps thrive—even in gravitationally complex stellar neighborhoods."
RESEARCH PAPERS*
Aniket Sanghi et al., Worlds Next Door:A Candidate Giant Planet Imaged in the Habitable Zone of α Cen A. II,
arXiv (2025)
Charles Beichman et al., Worlds Next Door:
Charles Beichman et al., Worlds Next Door:A Candidate Giant Planet Imaged in the Habitable Zone of α Cen A. I,
arXiv (2025)
*Both papers accepted for publication in The Astrophysical Journal Letters
T.H.E.A.T.E.R.an.deR.G.L.ock+s.ee.se.aMee.rMor.e
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diät+5
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