First Direct Radio Detection from an Exoplanet Reveals Its Magnetic Field

An international team identified auroral radio bursts traced to the young gas-giant exoplanet Beta Pictoris b, 64 ly from Earth. Using the 64-dish MeerKAT array, they observed the system four times in 2025–2026. The emission, detected across 0.85–3.5 GHz, showed rapid, highly circularly polarized bursts—signatures of the electron cyclotron maser instability (ECMI). Precise astrometry (nine Gaia quasars and a VLBI calibrator) placed the source at Beta Pictoris b with 4.4 ? significance, ruling out the host star and nearby planet Beta Pictoris c.

South Africa’s MeerKAT array detects the first radio signal directly from an exoplanet ZME ScienceDiscovery Of Radio Emission From The Exoplanet ? Pictoris b Radio signals detected from a planet beyond our Solar System. Landmark discovery could help us search for habitable worlds The IndependentNewsweek

Direct magnetic-field measurements for exoplanets have been impossible. Earlier radio searches either failed to detect a signal (e.g., a 2022 VLA pilot of eight directly imaged exoplanets) or could not separate planetary emission from stellar activity (a 2024 low-frequency search of Beta Pictoris b). The Beta Pictoris system’s geometry—magnetically quiet A6V star and a planet at ~10 AU—allows MeerKAT’s resolution to distinguish the two sources.

South Africa’s MeerKAT array detects the first radio signal directly from an exoplanet Radio signals detected from a planet beyond our Solar System. Landmark discovery could help us search for habitable worlds ZME ScienceNewsweekThe IndependentDiscovery Of Radio Emission From The Exoplanet ? Pictoris b

• Magnetic field strength: The highest detected frequency (3.5 GHz) implies a local field of at least 1.25 kilogauss (? 1,250 gauss). Earth’s surface field is ~0.5 gauss.

South Africa’s MeerKAT array detects the first radio signal directly from an exoplanet

• Planetary properties: Beta Pictoris b is a young giant with a mass about 12 Jupiter masses and a rotation period of 8–9 h, comparable to Jupiter’s 10-hour day.

Radio signals detected from a planet beyond our Solar System. Landmark discovery could help us search for habitable worlds

• Signal characteristics: Bursts are circularly polarized at 40–70 % and recur on timescales consistent with the planet’s rotation, suggesting magnetosphere-ionosphere coupling. Alternative mechanisms such as stellar-wind power or an Io-like moon interaction were calculated to be insufficient by more than an order of magnitude.

South Africa’s MeerKAT array detects the first radio signal directly from an exoplanet

Magnetic fields shape how atmospheres interact with stellar winds and can preserve atmospheric mass. NASA notes that loss of a global field, as on Mars, allowed solar-wind erosion that eliminated surface liquid water. While a magnetic field alone does not guarantee habitability, the detection shows a method that could be applied to rocky exoplanets, where magnetic shielding may be crucial for retaining atmospheres.

Newsweek

Independent astronomer Joe Callingham (University of Amsterdam) called the measurement “an incredibly exciting advancement” pending peer review.

The Independent

The preprint, posted on September 15 to arXiv, lists seven additional directly imaged giants as viable targets for the same astrometric technique. Researchers estimate that telescopes five to seven times more sensitive than current instruments could detect similar auroral signals. Next-generation facilities, including the forthcoming Square Kilometre Array (SKA), are expected to provide the necessary sensitivity, potentially extending magnetic-field studies to smaller, rocky planets.

South Africa’s MeerKAT array detects the first radio signal directly from an exoplanet

The geometry of Beta Pictoris b’s magnetosphere, the exact auroral power source, and any long-term variability remain uncertain. Continued monitoring across a broader frequency range could reveal higher-frequency emission, refine field estimates, and test the link between rotation and auroral modulation.

South Africa’s MeerKAT array detects the first radio signal directly from an exoplanet