Sonali Tiwary
Astronomers have detected the first direct radio emission from a planet outside our solar system, using the MeerKAT radio telescope array in South Africa. The signal came from β Pictoris b, a young giant planet orbiting a star about 63 light-years from Earth, and it gives scientists the first direct measurement of a magnetic field around an exoplanet.
The detection was made at frequencies between 0.85 and 3.5 gigahertz. The researchers infer a magnetic field of at least approximately 1.25 kilogauss at the source of the emission — a measurement that no previous method could provide for planets beyond our solar system.
This matters because magnetic fields govern how planets interact with stellar winds and charged particles, and how moons of giant planets interact with their host planet's magnetosphere. Until now, measuring those fields for planets around other stars wasn't possible.
What the Radio Signal Actually Is — and What It Isn't
The signal is auroral radio emission, not a broadcast. The radio emission is associated with the same auroral processes responsible for polar lights on Earth and radio bursts from Jupiter, though the radio signal itself is distinct from visible aurora. On Jupiter, we can detect this type of emission from Earth. On β Pictoris b, the researchers have now detected the equivalent using MeerKAT.
The detection is interpreted as electron-cyclotron maser radiation — a specific mechanism where electrons spiralling along magnetic field lines produce coherent radio bursts. This interpretation is consistent with aurora on solar system planets and provides the physical basis for inferring the magnetic field strength from the detected frequency range.
This is not evidence of artificial transmission or extraterrestrial communication. The signal is a natural product of the planet's magnetic environment.
What makes this "first" meaningful is specificity. Earlier radio observations of planetary systems could not unambiguously separate emission coming from the planet itself from emission coming from the host star. The new observations, published in a paper submitted to arXiv on September 15 (arXiv:2609.16720), tied the signal directly to β Pictoris b's orbital position and timing — confirming the planet as the source rather than the star.
β Pictoris b is a young planet, estimated at roughly 20–23 million years old, compared to Earth's 4.5 billion. Researchers expect young giant planets to retain stronger magnetic fields from the heat of their formation, making the β Pictoris system a useful laboratory for studying early planetary evolution and how planetary magnetic fields change over time.
The MeerKAT array, operated from the Karoo region of South Africa, consists of 64 dishes and operates at the frequencies where auroral emission from giant planets tends to peak. The β Pictoris system was observed on four occasions in 2025 and 2026 using MeerKAT's L and S band receivers.
For anyone following the broader question of what distinguishes planetary environments capable of supporting life, how planetary magnetic fields affect habitability is directly relevant. Future radio observations using this technique could provide another way to study magnetic environments around other exoplanets.
The paper is available as an arXiv preprint (arXiv:2609.16720) and has not yet undergone formal peer review.
Does the radio signal mean aliens?
No. The researchers interpret the emission as auroral radiation produced by charged particles interacting with β Pictoris b's magnetic field. The observation provides information about the planet's magnetism and is consistent with natural radio emissions detected from Jupiter and other solar system planets. It is not evidence of an artificial transmission or extraterrestrial communication.
