PASADENA, CA – November 2, 2025 – The interstellar object 3I/ATLAS has presented astronomers with a new cosmic puzzle, exhibiting unexpected non-gravitational acceleration as it made its closest approach to the Sun (perihelion) recently. Data obtained from observatories, including insights discussed by Harvard University's Professor Avi Loeb, indicates that the object's trajectory cannot be fully explained by gravitational forces alone, prompting comparisons to the enigmatic interstellar visitor 'Oumuamua.

The phenomenon, first reported on October 30, suggests that 3I/ATLAS is being propelled by some form of outgassing or another non-gravitational mechanism, similar to how comets behave. However, the exact nature of this acceleration and the composition of 3I/ATLAS remain subjects of intense scientific scrutiny.

The Anomaly Explained

According to analyses of its trajectory, 3I/ATLAS demonstrated a deviation from the path predicted solely by the gravitational pull of the Sun and planets. This "non-gravitational acceleration" implies that a force other than gravity is acting upon the object. For most comets, this is typically attributed to the sublimation of ice from their surfaces, which creates jets of gas and dust that subtly push the comet.

However, 3I/ATLAS, like 'Oumuamua before it, is an interstellar object, meaning it originated outside our solar system. Its unique trajectory and the sudden observation of this acceleration near perihelion underscore its alien nature. Data points, including those likely from instruments such as the Atacama Large Millimeter/submillimeter Array (ALMA), are crucial for understanding this behavior. NASA's Jet Propulsion Laboratory (JPL) is among the agencies tracking the object's path, providing the foundational trajectory data.

Echoes of 'Oumuamua

The reported acceleration immediately draws parallels to 'Oumuamua, the first confirmed interstellar object, which also exhibited non-gravitational acceleration in 2017. That observation led to various hypotheses, including significant outgassing of an unknown volatile, or more controversially, suggestions of an artificial origin, as championed by Professor Avi Loeb.

Professor Loeb, in his commentary published on October 31, notes the similarities with 'Oumuamua and emphasizes the importance of direct observation. While conventional explanations like outgassing are the primary scientific consideration, the lack of a visible cometary tail for both 'Oumuamua and potentially 3I/ATLAS at the time of their observed accelerations complicates a straightforward interpretation. The nature of the material being ejected, if any, remains a key question.

Scientific Community Weighs In

The scientific community is approaching the observations of 3I/ATLAS with cautious optimism and rigorous analysis. Astronomers are working to refine models of its trajectory and explore all plausible natural explanations. "Every new interstellar visitor offers an unprecedented opportunity to study material from other star systems," stated a representative from a leading astronomical institute, requesting anonymity due to ongoing data analysis. "Understanding these accelerations is critical to deciphering their composition and origin."

The debate surrounding such objects highlights a fundamental challenge in astronomy: distinguishing between highly unusual natural phenomena and potentially more exotic explanations. For 3I/ATLAS, the focus will be on obtaining further observations to determine if any outgassing is detectable, or if other, currently unknown forces are at play.

What's Next for 3I/ATLAS?

As 3I/ATLAS continues its journey through our solar system before heading back into interstellar space, astronomers will be using every available instrument to gather more data. High-resolution imaging, spectroscopic analysis to identify the composition of any emitted gases, and continued trajectory tracking are all paramount.

The trajectory of 3I/ATLAS with positions of the planets on October 31, 2025 (Credit: NASA/JPL), provides a snapshot of its journey. Scientists hope that detailed follow-up observations will provide the definitive evidence needed to explain its peculiar acceleration, whether it points to a new class of interstellar comets or something even more unexpected. The findings from 3I/ATLAS are expected to contribute significantly to our understanding of the broader galactic environment and the objects traversing it.