Astronomers recently picked up a strange radio signal from an object passing through our Solar System. The discovery was made on October 24 using the MeerKAT radio telescope in South Africa. Researchers detected hydroxyl radicals (OH) around the object, which gave off a unique radio signature.

“These molecules leave a distinct radio signature that telescopes like MeerKAT can pick up,” said Harvard professor Avi Loeb, who has been studying 3I/ATLAS since summer.

Analysis shows that the object’s surface temperature is around –45°F (–43°C). Scientists estimate that its diameter could be as large as six miles. “This signal constitutes the first radio detection of 3I/ATLAS,” added Professor Loeb.

Massive Material Eruption Observed

The discovery came shortly after 3I/ATLAS made a close pass by Earth, making it easier to study. Optical images taken on November 9 revealed that the object is releasing massive clouds of material. These plumes stretch nearly 600,000 miles toward the Sun and about 1.8 million miles in the opposite direction — roughly the same size as the Sun or Moon as seen in the sky.

At a distance of 203 million miles from Earth, these images offered the first clear view of the object’s powerful activity.

Comparison with ‘Oumuamua

According to Professor Loeb, 3I/ATLAS is at least three miles wide and may be twice that size. By contrast, the first-known interstellar object, 1I/‘Oumuamua, discovered in 2017, was only a few hundred feet across.

However, scientists are puzzled by 3I/ATLAS’s extreme behavior. If it were a typical comet, the streams of material would move much slower and would take months to reach such long distances. “The numbers defy a natural explanation,” said Professor Loeb. “The mass loss, rapid brightening near perihelion, and size point to an anomaly.”

Next Steps: Closer Observation Ahead

Scientists expect to learn more on December 19, when 3I/ATLAS will make its closest approach to Earth. Space telescopes like Hubble and Webb will observe its speed, composition, and total mass to determine whether it’s a normal icy comet or something more unusual — possibly involving artificial mechanisms that produce the material ejections with minimal mass loss.

NASA’s Juno spacecraft will also track the object on March 16, 2026, as it passes 33 million miles from Jupiter. It will use its dipole antenna to listen for low-frequency radio signals.

Linked to the 1977 “Wow!” Signal

Global observers are following the object closely, partly because its trajectory aligns within nine degrees of the direction of the famous 1977 “Wow!” radio signal — a mysterious burst that has puzzled scientists for decades.

“3I/ATLAS is giving us a rare opportunity to study an interstellar object in real time,” Loeb said. “Radio and optical data show that it is ejecting massive amounts of material at extraordinary speeds and is behaving in ways that challenge our understanding of natural comets.”