The interstellar comet 3I/ATLAS has sparked a renewed debate about the possibility of extraterrestrial life. On December 19, 2025, the comet made its closest approach to Earth, passing at a distance of approximately 270 million kilometres (168 million miles) while travelling at an astonishing 153,000 mph. This remarkable speed has led some scientists, notably Harvard physicist Avi Loeb, to propose that the object may not be a typical natural comet but could instead be a probe from an alien civilization.
Contrasting Views on 3I/ATLAS
As 3I/ATLAS continues its journey through our solar system, a fierce dispute has emerged. Loeb suggests that the chemical signatures detected in the comet’s coma—the cloud of gas and dust surrounding its nucleus—might indicate an artificial origin. He points specifically to the presence of nickel and iron atoms, raising questions about how these heavy elements could exist in such cold environments. In a blog post, he argued that the conditions in space are typically too frigid to vaporize such grains easily.
“At the distances at which comets are observed, the temperature is far too low to vaporise silicate, sulphide, and metallic grains that contain nickel and iron atoms,” Loeb explained.
Loeb’s provocative analogy likens the encounter with interstellar objects to a blind date, suggesting that the potential for alien technology could pose a threat. “You never know whether you have a friendly visitor as your dating partner or a serial killer,” he stated in an interview with Sky News.
NASA’s Firm Stance
In stark contrast, NASA has responded firmly to Loeb’s claims, asserting that there is “overwhelming evidence” supporting the idea that 3I/ATLAS is a natural comet. According to agency scientists, the object exhibits behavior typical of known comets. Tom Statler, a lead scientist at NASA, reiterated this perspective, stating, “It looks like a comet. It very, very strongly resembles, in just about every way, the comets that we know.”
Statler acknowledged that while 3I/ATLAS may have some unusual characteristics compared to familiar solar system comets, these differences do not necessitate an artificial explanation. He concluded that the evidence overwhelmingly supports the classification of the object as a natural body.
Regardless of its origins, 3I/ATLAS is now on its trajectory out of the solar system. Following its flyby of Earth, the comet is expected to pass Jupiter in early 2026, with further models predicting it will clear the orbital distances of Saturn, Uranus, and Neptune by 2028. Eventually, it will continue on a hyperbolic escape path, moving beyond the detection capabilities of current instruments as it ventures further into the interstellar medium.
The ongoing discussion surrounding 3I/ATLAS highlights the tension between traditional astronomical science and the quest for understanding potential signs of extraterrestrial life. As observers continue to monitor the comet’s journey, the implications of its composition and behavior will likely remain a topic of interest in both scientific and public discourse.
