Beta Pictoris b Explained: The First Exoplanet Caught on Radio

Astronomers using South Africa’s MeerKAT radio telescope array have reported rapid radio bursts from Beta Pictoris b, a giant planet about 63 to 64 light-years away, in a preprint that is awaiting peer review. The preprint reports that the bursts are a natural radio aurora implying a magnetic field of at least about 1,250 gauss at the planet. This explainer is pinned to Saturday, October 3, 2026, and is built on the paper itself rather than a press release.

What did astronomers report finding at Beta Pictoris b?

The preprint reports that MeerKAT detected rapid, recurring, highly circularly polarized radio bursts, plus fainter steady emission, at the position of Beta Pictoris b in four observing sessions between February 2025 and May 2026. The preprint, titled “Discovery of radio emission from the exoplanet β Pictoris b” (arXiv:2609.16720v1, dated September 15, 2026), is by Kevin Ortiz Ceballos and Edo Berger of the Center for Astrophysics | Harvard & Smithsonian and Yvette Cendes of the University of Oregon. Its arXiv listing is marked “Submitted” with no journal reference, and the preprint reports emission from 0.85 to 3.5 gigahertz with circular polarization of roughly 40% to 70%.

The preprint reports that the first session came from a wider survey of ultracool dwarfs and exoplanets, followed by longer observations once the source was seen. It lists four sessions, shown below with average flux in microjanskys (µJy) as labeled in its Figure 1. L and S are MeerKAT’s two receiver bands.

The preprint reports a brightest single burst of 307 µJy in the L band, and polarization that is left-handed in May 2025 and right-handed in May 2026, which the authors say fits an aurora.

What is Beta Pictoris b?

Beta Pictoris b is a young giant planet, about 12 times Jupiter’s mass, that circles the star Beta Pictoris at roughly 10 astronomical units, a little farther out than Saturn is from our Sun. The star lies in the southern constellation Pictor, the Painter’s Easel, at 19.63 parsecs (about 64 light-years) in the preprint, a distance often rounded to 63 light-years elsewhere. The planet’s orbit takes about 24 years, and the preprint puts its temperature near 1,700 kelvin. The system also holds a debris disk and at least three giant planets. A French team led by Anne-Marie Lagrange first reported the planet as a candidate in November 2008 from imaging with ESO’s Very Large Telescope, and follow-up observations in 2009 and 2010 established it as a planet.

How do the authors say the emission comes from the planet, not the star?

The authors report tying the radio image to the Gaia sky reference frame using nine quasars and one calibration source, which they say places the emission at planet b rather than at its host star or planet c. The preprint reports a match to planet b and an offset from the star at 4.4 sigma and from planet c at 4.8 sigma once systematic errors are counted; with statistical errors alone, the preprint reports 5.2 and 5.6 sigma. Sigma measures how unlikely an offset that large would be from measurement noise alone. The reported with-systematics figures sit below the 5-sigma bar often used for discovery claims, and they rest on one team’s analysis, so we do not round them up. The preprint reports further checks, including dropping reference sources, injecting fake sources and testing for ionospheric distortion, and says the host star’s own field is at most about a quarter of the strength the emission needs.

What is a radio aurora, and what does it say about the magnetic field?

A radio aurora is coherent radio emission from electrons accelerated along a planet’s magnetic field lines, and the preprint reports that the highest frequency seen sets a minimum for the field’s strength. The preprint identifies the bursts as electron cyclotron maser emission, the process behind radio aurorae at Jupiter and other planets in our solar system. In its relation the emission frequency is about 2.8 gigahertz per kilogauss, so a reported burst detected up to 3.5 gigahertz, the top of MeerKAT’s S band, requires at least about 1.25 kilogauss (1,250 gauss) at the emission site. The reported figure is a lower limit, not a measured surface value, though the preprint calls it the first direct magnetic-field measurement for an exoplanet.

NOAA puts Earth’s surface field at roughly 0.25 to 0.65 gauss, and NASA lists 4 to 13 gauss at Jupiter’s surface. By our arithmetic, the preprint’s floor of 1,250 gauss is roughly 2,000 to 5,000 times Earth’s field and nearly 100 times the top of Jupiter’s range. The preprint says the value fits a dynamo-scaling prediction of about 1.2 kilogauss at the surface for a young, massive giant planet.

Is this really the first radio detection from an exoplanet?

In the preprint’s wording, it is the first case of radio emission localized by position to a directly imaged exoplanet, which is narrower than the first hint of radio emission from any planet-hosting star. The preprint says earlier radio detections in planet-hosting systems could not be assigned to the planet rather than the star, and that searches of directly imaged giant planets had returned only upper limits. One was a late-2023 search of this very planet at 250 to 500 megahertz that set a limit of 0.18 millijansky. Per the preprint, ultracool dwarfs, including some down to the planetary-mass range, have shown similar bursts, and the authors use them as analogs.

Does this have anything to do with aliens?

No: the preprint attributes the reported emission to a natural process, a radio aurora driven by the planet’s magnetic field. In comments reported by science news outlets, co-author Yvette Cendes said it is not aliens but a very strong magnetic field. Some headlines have framed it differently, and nothing in the preprint supports that.

Who else has commented, and what is still unsettled?

As of October 3, 2026, the result is a preprint awaiting peer review, and we found no independent follow-up observations or journal publication reported. Joe Callingham of the University of Amsterdam, who was not involved, described the reported detection as a significant advance while calling it preliminary, and said radio pulses that track the planet’s rotation would add evidence. The preprint notes that an 8-hour gap between two L-band bursts is comparable to the planet’s roughly 9-hour rotation period, measured separately from JWST photometry, but calls it only a possible sign of such modulation. The preprint says continued monitoring could reveal the planet’s magnetic tilt, and that seven more directly imaged giant planets in five other systems within 45 parsecs (about 147 light-years) could be targeted with a 5- to 7-fold sensitivity gain the authors expect from next-generation radio observatories.

Can you see Beta Pictoris b or its star?

No amateur telescope can show the planet, but its host star is a naked-eye southern-sky star, about magnitude 3.9, that never rises for observers north of roughly 39 degrees north latitude. According to the preprint, the planet sits at most about 0.55 arcseconds from the star, a gap only large telescopes with special optics can split. The star’s declination is about minus 51 degrees, so even from southern Florida or the southern tip of Texas it peaks only around 13 degrees above the southern horizon, by our geometry. It is far better placed from the Southern Hemisphere.

What is the bottom line as of October 3, 2026?

A preprint awaiting peer review reports radio bursts from a giant planet 63 to 64 light-years away, and a magnetic field of at least 1,250 gauss at the emission site. The reported localization rests on one team’s analysis and falls below 5 sigma once systematics are included. Journal publication, revised numbers or follow-up observations would change the picture, and we will update this page if they are reported.