The interstellar object 3I/ATLAS has captured the attention of researchers as new findings suggest it possesses an anomalously large mass and size. In a recent study authored by Avi Loeb, Richard Cloete, and Peter Veres, data compiled from the Minor Planet Center between May 15 and September 23, 2025, were analyzed to determine the object’s characteristics. Remarkably, the study reveals that 3I/ATLAS has an estimated mass exceeding 33 billion tons and a diameter greater than 5 kilometers, making it notably more massive than previously discovered interstellar objects, 1I/`Oumuamua and 2I/Borisov.
The researchers utilized 4,022 observations from 227 observatories globally to examine the trajectory of 3I/ATLAS. The analysis indicated that the residual movement of the object was consistent with gravitational forces, resulting in a net upper limit of just 0.028 arcseconds on its positional shifts over a period of several months. This suggests that there was negligible non-gravitational acceleration affecting its course, which implies a significant mass for the object.
A key aspect of this research involved data from the Webb Space Telescope, which revealed a mass loss rate of approximately 150 kilograms per second and a high outflow speed of 440 meters per second from the object’s surface. These factors contribute to the conclusion that the nucleus of 3I/ATLAS is much larger than many of its interstellar counterparts, presenting a greater challenge to current theories about the mass distribution of rocky materials in exoplanetary systems.
As 3I/ATLAS approaches Mars on October 3, 2025, the HiRISE camera aboard the Mars Reconnaissance Orbiter will capture detailed images that could further refine our understanding of the object’s surface area and structure. Similar observational opportunities will arise in March 2026 when the object passes near the Juno spacecraft, yielding additional insights into its properties.
The mass and size of 3I/ATLAS raise intriguing questions regarding its origin and nature. The peculiar detection of nickel without iron has led to speculation about a technological origin, possibly suggesting that the object could be artificial rather than purely natural. This hypothesis aligns with the rare trajectory of 3I/ATLAS, prompting scientists to consider both natural and technological explanations for the object.
In summary, the study of 3I/ATLAS opens new avenues for exploration and discussion about interstellar objects and their classifications. As astronomers eagerly await further observations, there remains hope and curiosity about unraveling the mysteries associated with this enigmatic celestial entity. As Loeb emphasizes, scientific discovery is guided by data, fueling a collective curiosity to learn more about the cosmos.