{"id":253704,"date":"2025-11-09T20:49:09","date_gmt":"2025-11-09T20:49:09","guid":{"rendered":"https:\/\/www.newsbeep.com\/uk\/253704\/"},"modified":"2025-11-09T20:49:09","modified_gmt":"2025-11-09T20:49:09","slug":"the-remarkable-large-scale-structure-of-anti-tail-and-tail-jets-from-3i-atlas-by-avi-loeb-nov-2025","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/uk\/253704\/","title":{"rendered":"The Remarkable Large-Scale Structure of Anti-Tail and Tail Jets from 3I\/ATLAS | by Avi Loeb | Nov, 2025"},"content":{"rendered":"

\"Avi<\/a>Press enter or click to view image in full size\"\"A stacked deep image of 3I\/ATLAS, taken between 5:08\u20135:22 UT on November 9, 2025, through a combination of 5 exposures, each lasting 3 minutes, with two telescopes. The sunward direction is towards the lower left corner. (Credit: Frank Niebling and Michael Buechner, posted here<\/a>)<\/p>\n

Today, a magnificent large-scale image of the interstellar object 3I\/ATLAS<\/a>, was reported here<\/a> by Frank Niebling and Michael Buchner. The stacked image combines a series of 5 exposures, each lasting 3 minutes, from two telescopes (TEC 140\/f5 and ASI 6200MM) between 5:08\u20135:22 UT on November 9, 2029.<\/p>\n

The image shows two anti-tail jets out to 10 arcminutes towards the Sun accompanied by a longer collimated jet, extending away from the Sun out to an angular separation of 30 arcminutes, roughly the diameter of the Sun or the Moon.<\/p>\n

At the current distance of 3I\/ATLAS from Earth, 326 million kilometers, these angular extents correspond to spatial sizes of 0.95 million kilometers for the sunward anti-tail jets and 2.85 million kilometers for the tail jet away from the Sun. This enormous spatial scale is three orders of magnitude larger than the scale of the glowing halo around 3I\/ATLAS in the Hubble Space Telescope image from July 21, 2025 (reported here<\/a>).<\/p>\n

This multi-jet structure constitutes a remarkable target for future observations with the Hubble and Webb telescopes, as 3I\/ATLAS will arrive at closest approach to Earth on December 19, 2025. Its minimal distance from Earth will be 269 million kilometers, about a hundred times larger than the extent of the jet structure in today\u2019s images. It is therefore unlikely that particle probes on Earth-based satellites will be able to capture particles from these jets. The same holds for the particle detectors on NASA\u2019s Juno spacecraft around Jupiter (discussed here<\/a>), which will probe 3I\/ATLAS on March 16, 2026 from a distance of 53 million kilometers, an order of magnitude larger than the extent of the current jet structure. Similarly, ESA\u2019s Juice spacecraft on its way to Jupiter (discussed here<\/a>), is currently 64 million kilometers from 3I\/ATLAS and unable to intercept these jets.<\/p>\n

For a natural comet, the outflow velocity of the jets is expected to be merely 0.4 kilometers per second, of order the sound speed of gas at the distance of 3I\/ATLAS from the Sun. In order for the jets to extend over the observed scaless, they should have been ejected for timescales of 3 months for the tail and 1 month for the anti-tail.<\/p>\n

Given that the anti-tail jets are only stopped at a distance of ~1 million kilometers implies that their ram-pressure exceeds that of the solar wind out to that distance. The solar wind is flowing at a speed of about 400 kilometers per second, which is a thousand times larger than the outflow speed from a natural comet. Since ram-pressure scales as speed squared, this means that the outermost mass density in the anti-tail is a million times bigger than that of the solar wind \u2014 a few proton masses per cubic centimeters. The outermost mass density of the jet gives a mass flux of 2 million kilograms per second per million-kilometer square. Summing over an area of order 10 million-kilometer squared, yields a mass loss rate of 50 billion tons per month. This mass is comparable to the minimum mass associated with 3I\/ATLAS, 33 billion tons, that I calculated here<\/a> from the lack of non-gravitational acceleration in the months preceding October 2025. Assuming a solid density of 0.5 grams per cubic centimeters, this means that the diameter of 3I\/ATLAS must be bigger than 5 kilometers. If it is a natural comet and most of its nucleus survived perihelion, then the diameter of 3I\/ATLAS should be 10 kilometers or larger.<\/p>\n

This raises the first and most important anomaly that I pointed out in my first paper on 3I\/ATLAS, published here<\/a>. The inferred mass of over 50 billion tons is at least a million times more than the inferred mass of 1I\/`Oumuamua<\/a>. Why were we so fortunate to receive such a giant object as the third in the list of interstellar objects before witnessing a million objects of the size of 1I\/`Oumuamua? As I showed in my paper, there is not enough rocky material in interstellar space to accommodate the delivery of such a giant icy rock to the inner solar system over our survey period of a decade. We would expect an object with a diameter above 10 kilometers to be delivered to our vicinity once per ten thousand years or longer. This anomaly has a likelihood of less than 0.1% if all rocky materials are packaged in large bodies of this size or less than 0.0005% if there is equal amount of total mass per logarithmic package mass interval. Combine that with the 0.2% probability of the retrograde trajectory of 3I\/ATLAS being aligned to within 5 degrees with the ecliptic plane, and you get a chance of one in a hundred million for 3I\/ATLAS to originate at random from as a natural comet from interstellar space.<\/p>\n

If, however, we consider the possibility that the jets emanating from 3I\/ATLAS are associated with technological thrusters, then the required mass loss can be 1\u20132 orders of magnitude smaller with human-made technologies. Chemical rockets are propelled by an exhaust speed of 3\u20135 kilometers per second, which is ten times larger than the maximum ejection speed of volatiles sublimated by sunlight from cometary surfaces. Ion thrusters reach an even higher ejection speed of 10\u201350 kilometers per second. Furthermore, alien technology might employ thruster with yet higher speeds, reducing the required mass loss by more than 2 orders of magnitude and making the required fuel less than a percent of the mass of the spacecraft.<\/p>\n

Given these considerations, is 3I\/ATLAS of natural or technological origin?<\/p>\n

Upcoming spectroscopic observations will allow us to determine the velocity, mass flux and composition of its jets and hence answer this foundational question.<\/p>\n

The foundation of pioneering scientific research is the humility to learn rather than the arrogance of expertise.<\/p>\n

ABOUT THE AUTHOR<\/p>\n

Press enter or click to view image in full size\"\"(Image Credit: Chris Michel, National Academy of Sciences, 2023)<\/p>\n

Avi Loeb is the head of the Galileo Project, founding director of Harvard University\u2019s \u2014 Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011\u20132020). He is a former member of the President\u2019s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of \u201cExtraterrestrial:<\/a> The First Sign of Intelligent Life Beyond Earth<\/a>\u201d and a co-author of the textbook \u201cLife in the Cosmos<\/a>\u201d, both published in 2021. The paperback edition of his new book, titled \u201cInterstellar<\/a>\u201d, was published in August 2024.<\/p>\n","protected":false},"excerpt":{"rendered":"Press enter or click to view image in full sizeA stacked deep image of 3I\/ATLAS, taken between 5:08\u20135:22…\n","protected":false},"author":2,"featured_media":253705,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[24],"tags":[2302,90,56,54,55],"class_list":{"0":"post-253704","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-physics","8":"tag-physics","9":"tag-science","10":"tag-uk","11":"tag-united-kingdom","12":"tag-unitedkingdom"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/253704","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/comments?post=253704"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/253704\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media\/253705"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media?parent=253704"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/categories?post=253704"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/tags?post=253704"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}