The Symmetric Jet Structure in Hubble Images of 3I/ATLAS
-
Similar Topics
-
By DisclosureWatch
The recent release of the first images from ESA's JUICE mission has stirred a lot of buzz in the astronomy community. Seeing Jupiter's moons up close for the first time is truly stunning. It's interesting to note how different each moon looks, with some appearing icy and others showing signs of geological activity. Do you think these differences could hint at varying histories or potential for life?
I'm particularly intrigued by Ganymede’s surface features. The images reveal a mix of bright and dark regions, suggesting a complex geologic past. It's fascinating to think about what processes could have shaped such a landscape. So, how do you all interpret these features based on what we know?
Also, I noticed some commentary about Callisto and its heavily cratered surface. Many are wondering if its age could impact our understanding of the moon's history and potential future explorations. Are there theories out there that suggest why some moons are more geologically active than others?
I can't help but think about how this mission will inform our understanding of the broader context of the Jupiter system. With the data coming in, we might be able to draw parallels to other celestial bodies in our solar system. Do you think this could reshape our ideas about habitability in extreme environments?
As we await more data from JUICE, I wonder what specific aspects of these moons you find most exciting or puzzling. Which features do you think will provide the most groundbreaking insights into our understanding of the Jovian system? Let's keep the conversation going as more images and data come in!
-
By Avi Loeb Medium
The symmetric system of three jets emanating from the nucleus of the interstellar object 3I/ATLAS (separately from the primary anti-tail jet) after the circularly symmetric glow was removed by the Larson-Sekanina rotational gradient filter, based on a Hubble Space Telescope image taken on November 30, 2025. (Image credit: T. Scarmato and A. Loeb 2026)A new paper (accessible here) that I co-authored today with Toni Scarmato analyzed images of the interstellar object 3I/ATLAS, taken by the Hubble Space Telescope over the past five months. After removing the circularly-symmetric glow around the nucleus of 3I/ATLAS using the Larson-Sekanina rotational gradient filter, we identified three jets emanating from the nucleus that are equally separated from each other in sky projection by about 120 degrees in addition to a primary anti-tail jet pointed at the Sun.
Whether these jets are technological thrusters or pockets of ice that happened to be oriented symmetrically on the surface of a natural iceberg, the outflows of gas and dust in these three jets exerted thrusts through the rocket effect, which resulted in the observed non-gravitational acceleration of 3I/ATLAS (as summarized in a paper that I co-authored with Valentin Thoss and Andi Burkert, accessible here). Our new paper links, for the first time, the directions and momentum flows in these three jets to the non-gravitational acceleration of 3I/ATLAS.
In our previous paper (accessible here), we demonstrated that the jet system wobbles with a period of 7.2 hours, likely as a result the rotation of the nucleus. We concluded that the jet structure wobbles around the rotation axis with a characteristic angular excursion of about 20 degrees, and the rotation axis is aligned with the sunward direction to within about 20 degrees.
Building on this inferred jet system and periodic wobble analysis of 3I/ATLAS, our new paper measures the observed jet position angles and links them to the non-gravitational acceleration components in three dimensions. We use the sky projection and images of the three persistent jets to estimate the order-of-magnitude thrust that each of them provides to the nucleus. Altogether, our analysis provides consistency between the properties of the three jets and the inferred non-gravitational acceleration of 3I/ATLAS, strengthening the evidence that the rocket effect explains the deviations of its trajectory from the path expected from gravity alone.
We adopted the observed jet position angles (PAs) in the sky (with North=0◦, East=90◦) on November 30, 2025 as follows:
• Jet1: PA = 65◦, • Jet2: PA = 290◦, • Jet3: PA = 175◦.
Our analysis identifies Jet2 as the dominant contributor to the transverse non-gravitational acceleration. The table below shows the breakdown of the contributions from the three jets to the non-gravitational acceleration of 3I/ATLAS, a [with components (A1,A2,A3)], in meters per second squared:
The complete set of Hubble Space Telescope (HST) images is available here.
The symmetric configuration of three jets plus the anti-tail jet raises the question of whether they might constitute a technological system designed for stabilizing the trajectory of 3I/ATLAS. A recent paper by Bo Andree (accessible here) suggested that the
minimal approach for steering an interstellar comet along a controlled trajectory indeed matches this 3+1 jet configuration. By relaxing the full six-degree-of-freedom control to forward-cone steering — sufficient for practical navigation — the paper showed that four thrusters are required: one primary jet and three secondary jets separated symmetrically by 120 degrees from each other. The secondary 3-jets synthesize continuous in-plane steering, while the primary (anti-tail) jet provides low-bandwidth attitude shaping: as the body rotates, the primary-jet torque direction sweeps predictably over a cycle, enabling out-of-plane steering via phase-scheduled firing.
This highlights the fundamental question: is the observed 3+1 jet system around 3I/ATLAS a technological signature?
ABOUT THE AUTHOR
(Image Credit: Chris Michel, National Academy of Sciences, 2023)Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, former director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics (2005–2026), and the former chair of the astronomy department at Harvard University (2011–2020). He is a former member of the President’s 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 “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.
Professional website:
https://lweb.cfa.harvard.edu/~loeb/
Social media:
https://avi-loeb.medium.com/
https://www.youtube.com/@ProfessorAviLoeb
https://open.spotify.com/show/1zhndXkvSY2b8FdjspFpCd
https://x.com/ProfAviLoeb
View the full article
-
By Avi Loeb Medium
A false-color brightness map of 3I/ATLAS, taken on January 22, 2026 in a 170 second exposure by the WFC3 UVIS (F350LP) camera of the Hubble Space Telescope (left panel). The map was processed through a Larson-Sekanina Rotational Gradient filter, which removes the circularly symmetric glow around the nucleus showing four jets (right panel). The jet structure includes a prominent anti-tail directed at the Sun and Earth on that date, along with a system of three mini-jets surrounding the nucleus. These mini-jets are equally separated by an angle of 120 degrees from each other, but one of them (labeled by a position angle PA=120 degrees) is faint, possibly because it is hidden in an unfavorable orientation relative to Earth. (Image credit: Toni Scarmato, based on data released by NASA/ESA/STScI here)Good news. The rare cosmic alignment between the interstellar visitor 3I/ATLAS, the Earth and the Sun, was captured by the Hubble Space Telescope on January 22, 2026.
A new set of six 170 second exposures, taken by the Hubble Space Telescope between 13:10:30 and 13:43:33 UTC on January 22, 2026, were just posted here. The exposures display brightness maps of the glowing halo surrounding 3I/ATLAS. The glow is elongated by about 100,000 kilometers in the direction of the Sun, a length scale which is ten times larger than the Earth’s diameter.
In a new paper that I published with Mauro Barbieri here, we alerted astronomers to this “full Moon phase” of 3I/ATLAS when observers from Earth will see it from the direction of the Sun to within an extremely small misalignment angle of just 0.012 radians. This rare alignment resulted in a brightness surge whose magnitude and growth rate is dictated by the composition and structure of the particles shed by jets of 3I/ATLAS. No new data other than the Hubble images was made public as of yet.
When the Hubble images from the January 22, 2026 alignment were processed by my collaborator Toni Scarmato through the Larson-Sekanina Rotational Gradient filter — which removes the circularly symmetric glow around the nucleus, the residuals showed the system of 4 jets, including a prominent anti-tail directed nearly towards the Sun and Earth, supplemented by three mini-jets. The mini-jets are equally separated from each other by an angle of 120 degrees, and one of them (labeled by a position angle PA=120 degrees in the above image) is faint, possibly because it is hidden in an unfavorable orientation relative to Earth.
Among the 18 anomalies of 3I/ATLAS listed here, we still do not know the nature of the anti-tail that allows it to penetrate hundreds of thousands of kilometers through the Solar wind and radiation without being deflected away from the Sun, as often is the case in familiar cometary tails. Is the anti-tail composed of fragments of ice (as suggested in a paper I published with Eric Keto here), large dust grains (as I suggested here), or massive objects (as I published here)? The symmetric system of 3 mini-jets that supplement the anti-tail remains a potential technological signature (as discussed here).
As I explained in a new television interview an hour ago (posted here), there is still a lot to learn about 3I/ATLAS. The best is yet to come.
ABOUT THE AUTHOR
(Image Credit: Chris Michel, National Academy of Sciences, 2023)Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — 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 (2011–2020). He is a former member of the President’s 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 “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.
View the full article
-
By Avi Loeb Medium
False-color brightness map of 3I/ATLAS on January 14, 2026 in six 170 second exposures by the WFC3 UVIS (F350LP) camera of the Hubble Space Telescope (top image, spanning 130,000 kilometers on a side). The map was processed through a Larson-Sekanina Rotational Gradient filter, which removes the circularly symmetric glow around the nucleus (bottom image), showing four jets. The jet structure includes a prominent anti-tail, directed at the Sun towards the lower left, along with a system of three mini-jets. These mini-jets are equally separated by an angle of 120 degrees from each other, but none of them is pointing away from the Sun as expected for a standard cometary tail. (Image credit: Toni Scarmato, based on data released by NASA/ESA/STScI here)A new set of six images, taken by the Hubble Space Telescope on January 14, 2026, show the brightness map of the glowing halo surrounding 3I/ATLAS after perihelion. The glow extends beyond 130,000 kilometers towards the Sun, about a third of the Earth-Moon separation.
When the image is processed through the Larson-Sekanina Rotational Gradient filter which removes the circularly symmetric glow around the nucleus, it features a weird configuration of jets, including a prominent anti-tail outflow directed towards the Sun, supplemented by a system of three mini-jets. These mini-jets are equally separated by an angle of 120 degrees from each other, and none of them is pointing away from the Sun as expected for a standard cometary tail.
The last Hubble exposure ends half an hour after the first exposure starts. A new paper that I co-authored with Toni Scarmato (accessible here) analyzed previous Hubble images from December 2025 and concluded that the jet structure wobbles periodically by +/-20 degrees over a period of 7.1 hours. This implies a modest shift by 5.6 degrees over 0.5 hours in the orientation of the jet system on January 14, 2026.
On January 22, 2026, the Earth will be aligned to within 0.69 degrees with the line connecting 3I/ATLAS to the Sun (as reported in the new paper I co-authored with Mauro Barbieri here). Just as in the context of a full Moon, this rare alignment will allow us to see 3I/ATLAS and the glowing dust around it in full brightness when the area of their reflecting surfaces will be maximized. Since we will be observing 3I/ATLAS from the direction of the Sun on that date, its sunward anti-tail will be pointed at us.
Measurements of the brightness surge and polarization of 3I/ATLAS at opposition to the Sun could shed new light on the composition and size of the fragments it launches into the anti-tail.
What is the nature of the anti-tail that allows it to penetrate hundreds of thousands of kilometers through the Solar wind and radiation without being deflected away from the Sun, as often the case in familiar cometary tails? Is the anti-tail composed of fragments of ice (as suggested in a paper I co-authored with Eric Keto, published here), large dust grains (as I suggested in a research note, posted here), or massive objects (as I suggested in a paper, published here)?
Data from the SPHEREx space observatory indicated the existence of icy fragments around 3I/ATLAS before perihelion (as reported here in August 2025). However, the spectral signature of ice disappeared in the SPHEREx data after perihelion, taken during December 2025 (as reported here), when abundant organic molecules in gas phase, such as CH3OH, H2CO, CH4, and C2H6, were discovered, along with an enhancement by a factor of ~20 in the water production rate. To survive cosmic-ray bombardment along an interstellar journey that lasted billions of years, these organic molecules must have been buried under a thick layer of material, at least 10-meters in depth.
ABOUT THE AUTHOR
(Image Credit: Chris Michel, National Academy of Sciences, 2023)Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — 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 (2011–2020). He is a former member of the President’s 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 “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.
View the full article
-
By Avi Loeb Medium
Top panel: Images of 3I/ATLAS, taken in the wavelength range of 0.75–5.0 microns between the 8 and 15 of December, 2025. Each image spans 300,00 kilometers on a side. The brightness contours represent 5, 20 and 50 times the background noise; color bars are in mega-Jansky per steradian. The celestial North-and-East directions are shown by black arrows, along with the anti-velocity (dashed-blue) and anti-sun (solid-red) directions. On these large scales, the brightness map of dust and organics was found to be pear-shaped, with an anti-tail elongation in the direction of the Sun. All six other gas plumes were found to be nearly round. Middle panel: Flux spectrophotometry (points), colored by observation date (right color bar) and normalized to equal distances between 3I/ATLAS, the Earth, the Sun (=1 AU). The major spectral emissions of various gas species [CN(0.93microns), H2O(2.7–2.8 microns), Organics(3.2–3.6 microns), CO2(4.2–4.3 microns), and CO(4.7–4.8 microns)] have been color coded. Bottom: Reflectance-Spectrum, given by the flux ratio between 3I/ATLAS and the Sun. The dust spectrum can be described by scattered sunlight and thermal emission. The signature of sub-micron dust particles that would have enhanced the blue color via Rayleigh scattering are absent. Moreover, these small particles would have also been subjected to strong solar radiation-pressure effects and would have formed the standard cometary tail, extending away from the Sun — which is not observed. (Credit: C.M. Lisse et al. 2026)A new paper led by Carey Lisse (accessible here) reports large-scale images of the gas plume around the interstellar object 3I/ATLAS after perihelion, based on data collected last month by the SPHEREx space observatory. The data show enhanced mass loss of dust and gas around 3I/ATLAS.
The new images of 3I/ATLAS were taken in the wavelength range of 0.75–5.0 microns between the 8 and 15 of December, 2025. Each image spans 300,00 kilometers on a side. On these large scales, the brightness maps of dust and organics were found to be pear-shaped, with an anti-tail elongation in the direction of the Sun. All six other gas plumes were found to be nearly round. The major gas species were identified as: cyanide (CN, at a wavelength of 0.93 microns), water (H2O, in the wavelength range of 2.7–2.8 microns), Organics (C-H, between 3.2–3.6 microns), carbon-dioxide (CO2, 4.2–4.3 microns), and carbon-monoxide (CO, 4.7–4.8 microns). The CO2 gas-plume continues to extend out to a few hundreds of thousands of kilometers. The dust spectrum can be described as the sum of scattered sunlight and thermal emission.
Most notably, the signature of sub-micron dust particles that would have enhanced the blue color via Rayleigh scattering are absent. Moreover, these small particles would have also been subjected to a strong solar radiation-pressure and would have formed the standard cometary tail, extending away from the Sun — which is not observed — as I argued in an essay, posted here on December 25, 2026.
Compared to the pre-perihelion data reported from SPHEREx in August 2025, the continuum spectral signature of water-ice absorption has mostly disappeared, replaced by scattered-light plus thermal-emission from organo-silicaceous dust grains, while the water-gas emission is twenty times (!) brighter than it was before perihelion. The new appearance of cyanide (CN) and organic features suggests that these species are contained in the water phases.
The new mass loss rate of water (H2O) is 180 kilograms per second, similar to the new mass loss rate of carbon dioxide (CO2), with both being two-thirds of the carbon-monoxide (CO) mass loss rate. The brightness maps suggest that cyanide and organics are sourced from the dust, while the H2O, CO2, and CO-gas originate from a symmetric region centered on the nucleus.
The pear-shaped dust anti-tail is consistent with large dust grains. The gas production of 3I/ATLAS had been shown to be dominated by icy fragments in the pre-perihelion imaging of 3I/ATLAS by SPHEREx (as reported here and argued in the paper I co-authored with Eric Keto here). These fragments would have had to be thick, possible more than 10-meters in diameter, in order to preserve deep unprocessed material. Last month, I published a paper here, explaining the large extent of the anti-tail glow towards the Sun in this context.
As the authors of the new paper admit, this inference raises a new anomaly concerning 3I/ATLAS. It implies a huge amount of dust mass, because these same large boulders have to provide enough surface area to make the gas plume a hundred times brighter than the nucleus in reflected sunlight. We know that the fragments must be larger than a millimeter, because there is no evidence for a radiation-pressure dominated cometary tail of fine dust.
The nature of the scattered sunlight in the glowing halo around 3I/ATLAS has also fundamentally changed around perihelion, from an ice-dominated reflectance spectrum into that of low-albedo dust dominated by bluish light scattering.
The SPHEREx data demonstrates once again that science is a learning experience. We need more data to guide us about the proper resolution of the above-mentioned anomaly. We should not be surprised to find out that objects arriving at our cosmic backyard in the inner solar system from the cosmic street of interstellar space, are different from the familiar icy rocks we had seen before.
ABOUT THE AUTHOR
(Image Credit: Chris Michel, National Academy of Sciences, 2023)Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — 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 (2011–2020). He is a former member of the President’s 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 “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.
View the full article
-
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.