Astronomers Detect First Direct Radio Signals From Exoplanet Beta Pictoris b, Revealing Magnetic Field Strength

Astronomers have successfully detected radio signals emanating directly from the exoplanet Beta Pictoris b, allowing them to measure its magnetic field for the first time. Using the MeerKAT radio telescope array in South Africa, an international team isolated the auroral emissions from the gas giant, which sits roughly 63 light-years from Earth.[1][2]

The radio waves are produced by a phenomenon known as the electron cyclotron maser instability. As electrically charged particles spiral along the planet's magnetic field lines toward its polar regions, they excite molecules in the atmosphere. This process generates both glowing auroras—similar to the northern and southern lights on Earth—and highly circularly polarized radio bursts.[1][7]

Because the highest frequency of these radio waves is directly tied to the strength of the magnetic field generating them, the researchers could calculate the planet's magnetic power. The detected frequencies, which reached up to 3.5 gigahertz, indicate that Beta Pictoris b possesses a local magnetic field of at least 1.25 kilogauss.[1][3]

For comparison, Earth's surface magnetic field measures roughly 0.5 gauss, making the exoplanet's field thousands of times stronger. "Here, we report the first direct detection of auroral radio emission from an exoplanet, the giant planet β Pictoris b, with the MeerKAT array," the research team, led by Kevin N. Ortiz Ceballos of the Center for Astrophysics | Harvard & Smithsonian, wrote in their September 2026 preprint.[1][2]

Beta Pictoris b is a massive, young gas giant, estimated to be 10 to 12 times the mass of Jupiter and only about 20 million years old. It rotates rapidly—completing a day in roughly eight or nine hours—and still radiates intense heat from its formation.[2][4]

This vigorous internal convection, combined with its fast spin, is believed to drive the powerful magnetic dynamo responsible for the intense auroral radio emissions. The new radio measurement provides the first direct observational test of dynamo scaling laws for a confirmed exoplanet, placing it exactly in the regime predicted by models calibrated on solar system planets.[1][3]

Astronomers have spent years searching for radio signals from planets beyond the solar system, but distinguishing a planet's faint radio signature from the overwhelming noise of its host star has proven exceedingly difficult. Previous detections of coherent radio emission in other systems could not be definitively spatially assigned to the planet rather than the magnetically active star.[1][5]

To confirm the origin of the signal, the research team utilized distant quasars as stable cosmic reference points. By mapping the MeerKAT observations against these celestial anchors during observing sessions in 2025 and 2026, they proved with high statistical confidence that the radio emission source was spatially offset from the star and aligned perfectly with the planet's orbit.[1][6]

The ability to directly measure exoplanetary magnetic fields transitions the field from theoretical modeling to direct observational science. Magnetic fields are considered a crucial component of planetary habitability, as they shield atmospheres from being stripped away by harsh stellar winds.[2][7]

While Beta Pictoris b is a hostile gas giant incapable of supporting life as we know it, the techniques pioneered in this study lay the groundwork for future exploration. As next-generation radio observatories come online, astronomers hope to detect similar signals from other nearby giant planets, eventually paving the way to assess the magnetic shields of smaller, Earth-like worlds.[2][4]