{"id":41781,"date":"2025-09-27T21:39:09","date_gmt":"2025-09-27T21:39:09","guid":{"rendered":"https:\/\/www.newsbeep.com\/il\/41781\/"},"modified":"2025-09-27T21:39:09","modified_gmt":"2025-09-27T21:39:09","slug":"unusual-new-3i-atlas-discovery-suggests-the-interstellar-comet-is-anomalously-massive","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/il\/41781\/","title":{"rendered":"Unusual New 3I\/ATLAS Discovery Suggests the Interstellar Comet is \u201cAnomalously Massive\u201d"},"content":{"rendered":"

The mysterious comet 3I\/ATLAS<\/a> appears to be extremely large, making it orders of magnitude more massive than two other confirmed interstellar objects observed in our solar system in years past, a new study suggests.<\/p>\n

Based on a new analysis of the most precise tracking data collected on the object<\/a> since its discovery in July<\/a>, the interstellar comet appears to be \u201canomalously massive<\/a>,\u201d a finding that raises new questions regarding our expectations about interstellar objects that occasionally traverse our solar system.<\/p>\n

The research was detailed in a new paper by Richard Cloete, Peter Vere, and Harvard astronomer Avi Loeb, which places new limits on the object\u2019s apparent non-gravitational acceleration and overall mass.<\/p>\n

The new findings are largely consistent with existing upper estimates for the unusual space object\u2019s size, with some recent observations suggesting it could be up to three miles long.<\/p>\n

An \u201cAnomalously Massive\u201d Interstellar Object<\/p>\n

More than four months of optical measurements collected on 3I\/ATLAS<\/a>, compiled by the Minor Planet Center, were used by the team for their analysis, which compared 3I\/ATLAS\u2019s position to the trajectory that would be expected based on gravity alone.<\/p>\n

Based on their results, the team found almost no measurable deviation from a gravitational path, which seems to point to the fact that the interstellar comet is experiencing some degree of non-gravitational acceleration, albeit a negligible amount.<\/p>\n

\"3I\/ATLASA recent deep image of 3I\/ATLAS, captured by the Gemini Multi-Object Spectrograph on Gemini South at Cerro Pach\u00f3n in Chile. Credit: International Gemini Observatory\/NOIRLab\/NSF\/AURA\/Shadow the Scientist
Image Processing: J. Miller & M. Rodriguez (International Gemini Observatory\/NSF NOIRLab), T.A. Rector (University of Alaska Anchorage\/NSF NOIRLab), M. Zamani (NSF NOIRLab).<\/p>\n

This finding would also seem to suggest that the object\u2019s nucleus must possess a minimum diameter of roughly five kilometers (slightly more than three miles), which makes it several orders of magnitude more massive than the first two known interstellar objects, \u02bbOumuamua and Borisov.<\/p>\n

Between May and September, more than 4,000 astrometric measurements related to the motion of 3I\/ATLAS were collected from 227 observatories around the world. Based on this data, an upper limit on non-gravitational acceleration for the interstellar comet could be calculated, which was less than 15 meters per day squared.<\/p>\n

According to the team\u2019s study, this finding, with consideration for the principle of momentum conservation, suggests that gas jets produced on the surface of the object as it continues to be warmed by heat from the Sun should result in a measurable push. Based on current observations, however, the lack of detectable deviation exhibited by the object appears to imply that 3I\/ATLAS is quite massive.<\/p>\n

Webb Data Suggests a Massive Object<\/p>\n

Additional data obtained from observations in early August by the James Webb Space Telescope reveal an estimated mass loss for 3I\/ATLAS of around 150 kilograms per second, with a calculated gas outflow of about 440 meters per second. These values, when factored into momentum-balance equations, indicate that the comet\u2019s nucleus likely possesses a minimum mass of 33 billion tons; this would mean that the comet would likely be at least five kilometers (slightly more than three miles) in diameter, if it is indeed composed of solid, ice-rich material.<\/p>\n

The team\u2019s newest estimate for the diameter of 3I\/ATLAS is close to previously reported higher-range estimates for its size based on images obtained by the Hubble Space Telescope, with both estimates now appearing to indicate the object is larger than its two known predecessors.<\/p>\n

\"3I\/ATLAS\"Above: Hubble Telescope image of the mysterious interstellar comet 3I\/ATLAS (Image Credit: ESA\/Hubble).<\/p>\n

Additionally, the team reports that the object\u2019s nucleus has remained its brightest and most stable point in imagery collected since its discovery, which includes recent images obtained by Gemini South in late August<\/a>, which first revealed the appearance of a conventional cometary tail.<\/p>\n

This, the researchers say, offers additional support for the conclusion that 3I\/ATLAS is extremely massive, since it appears to easily resist being deviated from its present course by outgassing from its Sun-facing side observed by astronomers over the last several weeks.<\/p>\n

In an email to The Debrief, Avi Loeb said the fact that 3\/ATLAS appears to be so much more massive than the first confirmed interstellar object, \u2018Oumuamua, makes it very unusual, especially when considering astronomers\u2019 expectations about the limited amount of rocky material that should proliferate throughout interstellar space.<\/p>\n

\u201cWe should have detected an order of 100,000 \u2018Oumuamuas before discovering an object as big as 3I\/ATLAS,\u201d Loeb told The Debrief, pointing to a paper he published in July,<\/a> which initially suggested that 3I\/ATLAS was either smaller or perhaps rarer than it looks. Loeb\u2019s July paper, he explains, \u201cshowed that we should have found such an object less than once per ten thousand years.\u201d<\/p>\n

Although he and his colleagues place new constraints on the object\u2019s size in their recent paper, the latest observations offer few additional clues about the interstellar object\u2019s composition than what could be gleaned during earlier observations by NASA\u2019s James Webb telescope<\/a> and SPHEREx infrared space observatory<\/a>.<\/p>\n

\u201cThe only hint about the composition is from the JWST and SPHEREx spectroscopy which indicated CO2 (87%), CO (9%) and H2O (4%) mass fractions,\u201d Loeb told The Debrief. \u201cVLT spectroscopy indicated rapidly rising trace amounts of cyanide and nickel without iron.\u201d<\/p>\n

\u201cThe lower limit that I derived in the new paper on the mass and size does not constrain the composition,\u201d Loeb said.<\/p>\n

Overall, based on the recent astrometric data Loeb and his colleagues analyzed for their study, Loeb says that the object\u2019s surprisingly large mass makes it all the more intriguing.<\/p>\n

\u201cGiven that massive objects are rare, the alignment of the trajectory of 3I\/ATLAS with the orbital plane of the planets around the Sun (to within 5 degrees) is even more tantalizing,\u201d Loeb told The Debrief. \u201cWhy would the first massive object possess this alignment?\u201d<\/p>\n

\"3I\/ATLASRecent imagery obtained by NASA\u2019s James Webb Space Telescope of the interstellar object 3I\/ATLAS provided astronomers with spectroscopic data that offered some of the best data presently available about the object\u2019s material composition (Credit: NASA\/James Webb Space Telescope).
\nControversial Possibilities<\/p>\n

In recent weeks, Loeb has frequently suggested an intriguing\u2014and controversial\u2014possibility: that 3I\/ATLAS might be something more complex than just a comet. As support for this unconventional view, the Harvard astronomer points not only to the object\u2019s unusual mass but also to its trajectory, which brings it close to Jupiter and Mars, as well as the jet-like glow the object exhibited during observations in July and August, and notably, the detection of nickel and iron in spectrographic observations by the Webb Telescope and SPHEREx missions.<\/p>\n

\u201cThe detection of nickel without\u00a0iron is only known to exist in industrially produced alloys, made through the artificial carbonyl chemical pathway,\u201d Loeb told The Debrief. \u201cEach of these anomalies has a small probability given our knowledge base on solar system comets and the interstellar comet 2I\/Borisov.\u201d<\/p>\n

\u201cIf you combine all of them, the probability is extremely small for it to belong to their class,\u201d Loeb maintains.<\/p>\n

Such anomalies, he contends, leave open the possibility that while 3I\/ATLAS may exhibit several comet-like attributes, it could in fact be something else entirely. For Loeb, this might even include the remote chance that astronomers are seeing an object of technological origin<\/a>.<\/p>\n

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However, most experts are hesitant to entertain such ideas. Tom Statler, NASA\u2019s Lead Scientist for Solar System Small Bodies in the Planetary Science Division at NASA\u2019s Washington Headquarters, recently told The Guardian<\/a> that while 3I\/ATLAS does exhibit several interesting properties<\/a>, \u201cit behaves like a comet,\u201d adding that \u201cthe evidence is overwhelmingly pointing to this object being a natural body.\u201d<\/p>\n

\u201cIt\u2019s a comet,\u201d Statler affirmed.<\/p>\n

Lingering Questions<\/p>\n

While the debate over 3I\/ATLAS is likely to continue as the object makes its closest approach to Mars<\/a> on October 3, current observations have raised several intriguing questions.<\/p>\n

For instance, such a large nucleus introduces a puzzle in terms of our expectations about interstellar object populations. If comets like \u2018Oumuamua are more common than previously expected, and they are on what may be the smaller end of the interstellar object scale, this would seem to imply that astronomers should have detected as many as tens of thousands of them before detecting a three-mile-long object like 3I\/ATLAS.<\/p>\n

Loeb and his colleagues suggest that this may indicate, at very least, that current models of planetary system debris are far from complete. Additional observations in the days ahead\u2014namely those that will be possible using the HiRISE camera on board NASA\u2019s Mars Reconnaissance Orbiter\u2014could provide crucial new data on the 3I\/ATLAS\u2019s surface area. Additionally, next March, the object will pass close enough to Jupiter that additional data may be obtained using NASA\u2019s Juno spacecraft.<\/p>\n

If these flybys collect the data needed to place additional constraints on the object\u2019s size and other characteristics in the days ahead, it could raise further questions for astronomers that strain our present understanding of the interstellar reservoir of rocky material that is believed to exist out there.<\/p>\n

For Avi Loeb, the prospect of obtaining such new information is an exciting one.<\/p>\n

\u201cI can\u2019t wait for this data!\u201d Loeb told The Debrief.<\/p>\n

\u201cThe way to tell the difference between a dogmatist and a curious scientist is by flooding them with data,\u201d Loeb added.<\/p>\n

Despite the controversy that 3I\/ATLAS has managed to generate since its discovery, one thing that almost everyone agrees on is that it defies many of our expectations about how such objects should behave, and thereby causes us to have to reconsider our preconceptions about the kinds of objects that populate the vastness of interstellar space, as well as how many of them may be lurking out there in the cold, silent darkness between stars.<\/p>\n

The team\u2019s new paper, \u201cUpper Limit on the Non-Gravitational Acceleration and Lower Limits on the Nucleus Mass and Diameter of 3I\/ATLAS,\u201d is currently available online<\/a> on the website of the Harvard & Smithsonian Center for Astrophysics.<\/p>\n

Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at\u00a0micah@thedebrief.org<\/a>. Follow him on X\u00a0@MicahHanks<\/a>, and at\u00a0micahhanks.com<\/a>.<\/p>\n

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