NASA officials said the interstellar object 3I/ATLAS behaves like a comet and that current measurements show no evidence it is artificial. Detected July 1 by the ATLAS survey, the object was imaged by Hubble and later by the Mars Reconnaissance Orbiter; it reached perihelion on Oct. 30. Scientists noted an unusually high carbon-dioxide-to-water ratio but offered natural explanations such as formation environment or radiation exposure. The object is only the third confirmed interstellar visitor and offers a rare glimpse of material from another star system.
NASA Confirms Interstellar Visitor 3I/ATLAS Is a Comet, Pushes Back on Alien Claims
NASA officials said the interstellar object 3I/ATLAS behaves like a comet and that current measurements show no evidence it is artificial. Detected July 1 by the ATLAS survey, the object was imaged by Hubble and later by the Mars Reconnaissance Orbiter; it reached perihelion on Oct. 30. Scientists noted an unusually high carbon-dioxide-to-water ratio but offered natural explanations such as formation environment or radiation exposure. The object is only the third confirmed interstellar visitor and offers a rare glimpse of material from another star system.
08:17 PM, 11/20/2025Science
NASA held an hour-long briefing at the Goddard Space Flight Center to address weeks of online speculation about the interstellar object 3I/ATLAS, concluding that the object behaves like a natural comet and that current measurements provide no evidence it is artificial.
What NASA reported
Scientists said observations from multiple instruments — including the ATLAS survey telescope, the Hubble Space Telescope and the Mars Reconnaissance Orbiter (MRO) — show a small body made of rock, ice and dust that emits vapor as it warms, producing a characteristic coma. Hubble images captured a teardrop-shaped coma and estimated the nucleus size at roughly 1,400 feet to 3.5 miles across. MRO later imaged a bright, diffuse cloud of dust and ice; the object reached perihelion on Oct. 30 but was difficult to observe from Earth because our planet was on the far side of the Sun.
Composition and unusual features
Spectroscopic measurements indicate a higher carbon-dioxide-to-water ratio than is common in many solar-system comets. NASA scientists said that while this compositional difference is notable, there are well-understood natural explanations: carbon dioxide can sublimate at larger distances, ices may have been exposed to higher radiation, or the object could have formed in a region with more abundant CO2 ice.
"It looks and behaves like a comet, and all evidence points to it being a comet," said Amit Kshatriya, NASA's Associate Administrator. Shawn Domagal-Goldman added that the observed volatile ratios can be explained by natural processes or different formation environments.
Why skepticism grew
Public skepticism and alternative theories grew on social media after a recent government shutdown limited official updates, creating an information vacuum. High-profile suggestions from some scientists and attention from lawmakers amplified speculation that the object might be artificial. Viewers and social posts criticized the perceived quality of images and pointed to features such as a large halo and multiple jets as unusual.
NASA scientists pushed back by explaining the observational challenges: the object is far away and traveling at high speed, which limits spatial resolution and makes clear imaging difficult. As Tom Statler, lead scientist for small bodies, put it, observers are like spectators in a stadium with different cameras and imperfect vantage points.
Scientific significance
Even as NASA rejects artificial explanations, officials emphasized the scientific importance of 3I/ATLAS: it is only the third confirmed interstellar object observed and provides a rare sample of material formed around another star. Its composition and behavior offer clues about formation conditions in other stellar systems and, potentially, the history of volatile ices beyond our solar system.
In short, the totality of detections and measurements — from ATLAS to Hubble to MRO and spectroscopy — support the conclusion that 3I/ATLAS is a natural comet originating outside our solar system, while also posing intriguing questions about how comets can differ across the galaxy.