A giant planet may be hiding in our nearest stellar neighborhood

Space · Published 23 October 2026 Swipe more like this →

In short: The Alpha Centauri system is only 4 light-years away, yet finding planets there has been notoriously difficult. Now, the James Webb Space Telescope has provided the strongest evidence yet of a gas giant orbiting our closest Sun-like star. It is a triumph of custom engineering over extreme glare.

The Alpha Centauri triple star system is a primary target for exoplanet research due to its proximity. It consists of the binary stars Alpha Centauri A and B—both of which are Sun-like—and the faint red dwarf Proxima Centauri. While three planets have already been confirmed orbiting Proxima Centauri, identifying worlds around the brighter A and B stars has remained a significant challenge for astronomers.

Using its Mid-Infrared Instrument (MIRI), the James Webb Space Telescope (JWST) detected strong evidence of a gas giant orbiting Alpha Centauri A. This observation required a custom observing sequence developed by the Space Telescope Science Institute to manage the system's unique properties. Because these stars are so bright, close to Earth, and move rapidly across the sky, the team had to use a coronagraphic mask to block out Alpha Centauri A’s overwhelming light.

The discovery process involved meticulous planning, extensive computer modeling, and careful analysis to rule out false positives like background galaxies, passing asteroids, or detector artifacts. If confirmed, this planet would be the closest to Earth that orbits within the habitable zone of a Sun-like star. However, as a gas giant, it would not support life as we know it. Despite being optimized for distant galaxies, Webb's ability to probe our nearest neighbors offers a unique opportunity to gather data on planetary systems other than our own.

The findings have been accepted in two papers in The Astrophysical Journal Letters. This research highlights the shift from simply knowing what is out there to understanding the mechanisms of how we detect it, a focus shared by astrophysicists like Dr. Becky Smethurst, who emphasizes the importance of understanding the 'how' behind our cosmic knowledge.

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