In July, astronomers using the Asteroid Terrestrial-impact Last Alert System telescope in Chile made a surprising discovery. They found an object speeding through our solar system at a pace too fast to be captured by the Sun’s gravity. This object, nicknamed 3I/ATLAS, is only the third known interstellar object to pass through our solar system. It has sparked a lot of curiosity in the scientific community.
Most researchers believe 3I/ATLAS is a natural comet, made of ice and surrounded by a bright cloud of gas and dust. However, Harvard astronomer Avi Loeb thinks there might be a chance it’s an alien artifact sent by another civilization. Although Loeb admits that this idea is becoming less likely as more data comes in, scientists continue to search for signs of life.
When 3I/ATLAS was closest to Earth on December 19, researchers from the Breakthrough Listen project used the Green Bank Telescope, the largest single-dish radio telescope worldwide, to examine it. They were looking for any artificial signals, but unfortunately, they found none. The telescope didn’t detect any radio emissions coming from 3I/ATLAS. As the Search for Extraterrestrial Intelligence Institute noted, the object seems to behave like a natural comet.
According to the Breakthrough Listen team, 3I/ATLAS shows typical cometary features, such as a coma and a round nucleus. Their findings suggest it is largely a natural object. They stress that, despite only three such objects being known so far, it’s crucial to study them thoroughly in case they reveal something extraordinary.
Loeb continues to examine the unusual traits of 3I/ATLAS. He points out its large size and unique trajectory, which brings it close to Mars, Venus, and Jupiter in the future. However, experts mostly agree that it’s a massive snowball of carbon dioxide and water ice. This reduces the likelihood that it’s an alien probe. If an extraterrestrial civilization sent it, they might consider reaching out to us when it came close, especially since Earth sends out many radio signals.
Drawing on his own “Loeb scale,” which rates the likelihood of an object being of alien origin, Loeb initially placed 3I/ATLAS at a four. He has chosen not to update this rating until more data is available from its closest approach, which could take months to analyze.
This excitement around interstellar objects is relatively new. For instance, the first confirmed interstellar visitor, ‘Oumuamua, was discovered in 2017. Initially thought to be a comet, it showed behaviors that puzzled scientists and raised questions about its composition. Research on such objects continues to reveal their mysteries, shedding light on our understanding of the universe.
As we gather more information about 3I/ATLAS, it serves as a reminder of how much we still don’t know. Interstellar objects remind us that we’re only beginning to understand our cosmic neighborhood.
For more details about similar discoveries, check the SETI Institute.
