Astronomers pick up first-ever radio signal from an exoplanet — but it’s not aliens - CNN

Astronomers say they have directly detected the first-ever radio emission from a planet outside the solar system. The signal, however, is evidence of a colossal magnetic field — not intelligent life.

“I know radio signals are associated with searches for extraterrestrial intelligence,” said Edo Berger, a professor of astronomy at Harvard University. “But this is something very different.”

The discovery, described in a new paper awaiting publication in a peer-reviewed journal, traces repeating radio bursts that appear to come from the exoplanet Beta Pictoris b, located 63 light-years from Earth — a short distance, astronomically speaking. The gas giant, about 12 times the mass of Jupiter, is one of three planets orbiting a young star that is 1.75 times as massive as the sun.

Processes associated with the planet’s magnetic field produce the radio emission, according to Berger, a researcher at the Center for Astrophysics | Harvard & Smithsonian in Cambridge, Massachusetts. Specifically, the detection involves auroras similar to Earth’s northern lights — the spectacular displays sparked by magnetic storms involving charged particles from the sun. “In order to see radio waves that extend all the way to the frequencies that we observed, you need an incredibly strong magnetic field,” added Berger, a coauthor of the paper posted September 15 to the preprint platform ArXiv.

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Not all planets have a magnetic field. Those that have one benefit from a natural shield that deflects disruptive energy. Earth’s magnetic field, for example, protects our atmosphere from being stripped away by solar wind, a continuous outflow of plasma that contains charged particles like protons and electrons.

“The magnetic field on this planet is at least 200 times stronger than the magnetic field of Jupiter,” Berger said, referring to Beta Pictoris b. Jupiter’s magnetic field, according to NASA, is powerful enough to generate a magnetosphere — the region of space influenced by the magnetic field — that ranks as the largest structure in our solar system, stretching up to 2 million miles (3 million kilometers) toward the sun.

Jupiter’s field also creates striking auroras, when electrically charged particles spewed from volcanoes on its moon Io become trapped around the field’s poles. As the gas giant rotates, the charged particles emit a glow but also a radio signal. “As these very high-energy particles are spiraling inside the magnetic field, along with the aurora they also produce radio waves,” Berger said.

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Astronomers call this type of signal an auroral radio emission. The phenomenon has been previously observed from Jupiter, Saturn and the sun, as well as stars outside the solar system and cool objects known as brown dwarfs — an intermediate between a star and a planet. This type of signal is what Berger and his colleagues detected from Beta Pictoris b, which ultimately points to the presence of an intense magnetic field that’s causing auroras and the radio emission.

Magnetic fields have implications for the structure of exoplanets and their atmospheres, according to Berger. “Radio observations can give us a completely new view on planets beyond our system,” he said.

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A well-studied star system

There had been hints of radio emissions from exoplanets before, but none had been confirmed, largely because it couldn’t be ruled out that the source was actually the host star, said Joseph Callingham, an associate professor at the Anton Pannekoek Institute for Astronomy of the University of Amsterdam in the Netherlands.

“What is unique for this study is that they localise the emission to the planet itself, separate from the star,” Callingham, who was not involved in the new research, wrote in an email.

The Beta Pictoris system is astronomically very young at about 23 million years old compared with our own solar system’s age of 4.5 billion years. Beta Pictoris b — the planet from which the radio signal potentially originates — was discovered in 2008. Two additional planets, Beta Pictoris c and Beta Pictoris d, were discovered in 2019 and 2026, respectively.