By Callum 
In the summer of 2025, something extraordinary slipped quietly into our cosmic neighbourhood. It had been traveling for an estimated tens of millions of years, crossing the cold, dark void between star systems, born around a sun we may never identify. It was not from here. And it was not planning to stay. On July 1, 2025, the ATLAS survey telescope in Rio Hurtado, Chile, caught the first glimpse of what would become one of the most discussed astronomical objects in recent history: 3I/ATLAS, the third confirmed interstellar object ever observed passing through our Solar System.
What followed was an extraordinary few months of professional observation, global media coverage, scientific debate, and — in one of the most compelling chapters of modern citizen astronomy — a series of photographs taken by a Canadian amateur astrophotographer named Paul Craggs using a portable smart telescope that costs less than a decent smartphone. This article tells the full story of 3I/ATLAS, how it was discovered, what scientists learned about it, and how Craggs captured images of an interstellar visitor that went viral worldwide.
“A $550 telescope. A backyard in Ontario. And the clearest amateur images yet of an object that left another star system before humans existed.”
The designation 3I/ATLAS breaks down simply: the number 3 identifies it as the third known interstellar object, the letter I stands for interstellar, and ATLAS is the name of the detection system that found it. Formally catalogued as C/2025 N1 (ATLAS) by the Minor Planet Center (MPC), it joins an extraordinarily exclusive list that includes only two predecessors: 1I/ʻOumuamua, detected in 2017 by the Pan-STARRS telescope at Haleakalā Observatory in Hawaii, and 2I/Borisov, discovered in 2019 by Crimean amateur astronomer Gennady Borisov.
What separates interstellar objects from ordinary comets and asteroids is their trajectory. Objects born within our Solar System follow elliptical orbits — closed paths that loop around the Sun indefinitely. Interstellar visitors, by contrast, travel on hyperbolic trajectories: open curves that enter our system, swing around the Sun, and exit forever. 3I/ATLAS had an eccentricity of approximately 6 — a figure so extreme it left absolutely no ambiguity about its origin. It came from somewhere else, and it was not staying.
Discovery Date: July 1, 2025 (first reported to MPC)
Discovery Instrument: ATLAS telescope, Rio Hurtado, Chile
Formal Designation: C/2025 N1 / 3I/ATLAS
Nucleus Diameter: 440 meters to 5.6 kilometers (Hubble estimate, August 2025)
Orbital Eccentricity: Approximately 6 — definitively hyperbolic
Entry Speed: ~137,000 mph (221,000 km/h) at discovery
Perihelion Speed: ~153,000 mph (246,000 km/h) at closest Sun approach
Perihelion Date: Late October 2025 — just inside Mars’s orbit
Closest Earth Approach: December 19, 2025 — ~270 million km (1.8 AU)
Scientists confirmed its cometary nature — rather than classifying it as an asteroid like ʻOumuamua — through early observations from the Lowell Discovery Telescope in Arizona, the Canada-France-Hawaii Telescope (CFHT) at Mauna Kea, and the Deep Random Survey telescope in Chile, all of which detected a diffuse coma and faint tail-like elongation on July 2, 2025. The eminent planetary scientist David Jewitt of UCLA, working with colleague Jane Luu on the Nordic Optical Telescope at La Palma, confirmed the object was clearly active.
ATLAS — the Asteroid Terrestrial-impact Last Alert System — is a NASA-funded network of wide-field survey telescopes designed primarily to detect near-Earth objects that might pose a threat to our planet. Operating telescopes in Hawaii, Chile, South Africa, and the Canary Islands, ATLAS scans the entire visible sky multiple times each night, generating an enormous volume of detection data that is automatically processed for anything that moves or appears unexpectedly.
Pre-discovery analysis revealed that 3I/ATLAS had actually been imaged weeks before its official identification. The Zwicky Transient Facility (ZTF) at Caltech’s Palomar Observatory in San Diego County had captured it as early as June 14, 2025. NASA’s Transiting Exoplanet Survey Satellite (TESS) data later showed the comet may have been exhibiting cometary activity as early as May 7, 2025 — two full months before its formal discovery — when it was still approximately 6.4 astronomical units from the Sun. Amateur astronomer Sam Deen identified even earlier ATLAS pre-discovery observations stretching back to June 5, 2025.
The reason it evaded detection for so long is almost poetic: 3I/ATLAS was passing in front of the dense star fields of the Galactic Center, where the chaotic background of billions of stars made isolating a faint, fast-moving interloper extraordinarily difficult. By the time the MPC announced the discovery and assigned the 3I designation on July 2, it had already collected 122 observations from 31 different observatories.
Beyond the excitement of its interstellar origin, 3I/ATLAS proved genuinely unusual in its physical and chemical properties — different enough from both Solar System comets and its interstellar predecessor 2I/Borisov to generate significant scientific discussion.
Spectroscopic analysis revealed that the coma of 3I/ATLAS had a distinctly reddish color — consistent with D-type asteroids and with 2I/Borisov, and likely caused by irradiated organic compounds called tholins. A study published in August 2025 by Toni Santana-Ros and colleagues found that the coma became progressively redder throughout July 2025, suggesting an evolving composition as the comet’s increasing activity exposed fresh material. The coma itself was predominantly composed of relatively large dust grains several micrometers in radius — larger than typical for Solar System comets.
Polarimetric observations taken by researchers using the FORS2 instrument on the Very Large Telescope (VLT), the ALFOSC instrument on the Nordic Optical Telescope (NOT), and the FoReRo2 instrument at the Rozhen National Astronomical Observatory revealed something genuinely unprecedented. 3I/ATLAS displayed an extremely deep and narrow negative polarisation branch — a combination never previously observed in any asteroid or comet. This polarimetric signature was so unusual that researchers proposed 3I might represent a completely new category of small planetary body — an object with dust properties unlike anything in our Solar System’s inventory.
The global response was extraordinary. NASA mobilised multiple spacecraft and observatories to observe 3I/ATLAS before it departed. The Hubble Space Telescope imaged it on July 21, 2025, revealing a teardrop-shaped cocoon of dust around the nucleus. NASA’s Parker Solar Probe observed it from October 18 to November 5 using its WISPR instrument during approximately 10 images per day. The Europa Clipper mission observed it on November 6 from 102 million miles away. NASA’s Psyche spacecraft tracked it over eight hours in September. Even Mars missions participated: the Mars Reconnaissance Orbiter, the MAVEN orbiter capturing it in ultraviolet light, and the Perseverance rover on the Martian surface all imaged it. ESA’s XMM-Newton captured 20 hours of X-ray observations in December 2025. ESA’s JUICE spacecraft also observed it, though those images were embargoed until February 2026.
Three space agencies — NASA, ESA, and CNSA — all released imagery of 3I/ATLAS. And then a man in a backyard in Ontario, Canada, released images that in some respects appeared sharper.
Paul Craggs is a dedicated amateur astrophotographer based in Mallorytown, Ontario, Canada. His work spans galaxies, auroras, nebulae, and deep-sky objects, all shared freely and openly with the public through his social media presence — primarily on X (formerly Twitter) under the handle @craggs_paul. His stated mission is straightforward and genuine: to make astrophotography more accessible to everyone, particularly those who assume the hobby requires expensive, professional-grade equipment.
Craggs is not a career astronomer. He does not work at an observatory or hold an institutional affiliation. What he brings to the field is something equally valuable: patience, precision, a willingness to share his process openly, and the kind of persistent curiosity that leads someone to point a $550 telescope at a once-in-a-generation interstellar visitor in the small hours of the morning.
The instrument Craggs used to photograph 3I/ATLAS was a DWARFLAB Dwarf 3 — a portable smart telescope that weighs approximately 3 pounds and costs around $550 USD. It is designed for accessibility: compact, self-aligning, app-controlled, and capable of automatic stacking of multiple short exposures to reveal faint objects. It is emphatically not the kind of instrument typically associated with images that attract the attention of Harvard astrophysicists. Its small aperture and short focal length make it less sensitive than a professional observatory instrument by several orders of magnitude. Which is precisely what made what Craggs achieved so remarkable.
On November 22, 2025, Craggs posted three images of 3I/ATLAS to X with a simple caption: “Captured 3I Atlas last night with my Dwarf 3.” The images circulated rapidly. They showed what appeared to be a clearly defined, structured object — a form that struck many observers as unusually crisp given the equipment involved, and which several commentators noted seemed to show less of the expected cometary tail structure than other images from the same period.
Two days later, despite worsening conditions, he posted again: “3I Atlas this morning! Clouds rolled in so couldn’t get more than a few pics with only 30 second exposure.” Even the follow-up images captured from degraded conditions showed clear coma detail. Coverage followed from International Business Times (US and UK editions), Zee News India, Mashable India, and All Day Astronomy among many others. The headlines were variations on the same theme: an amateur with a consumer telescope had produced images that compared favourably with those from institutions spending hundreds of millions of dollars to observe the same object.
The viral coverage drew the attention of Professor Avi Loeb, the Frank B. Baird Jr. Professor of Science at Harvard University and founding director of Harvard’s Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, former chair of the Harvard astronomy department, and head of the Galileo Project. Loeb is also the author of the bestselling book Extraterrestrial: The First Sign of Intelligent Life Beyond Earth and has been among the most prominent voices suggesting that ʻOumuamua might have been artificial in origin — a position the mainstream scientific community has not endorsed.
In a Medium post published on November 25, 2025, Loeb addressed the Craggs images directly and with admirable scientific precision. He noted that the unusually elongated appearance of 3I/ATLAS in Craggs’s captures might have resulted from motion smearing — an imaging artifact that occurs when a fast-moving object streaks slightly across the sensor during exposure. The Dwarf 3’s relatively short focal length and the comet’s significant angular velocity at the time made this a plausible and important technical explanation for some of what observers found striking about the images.
This was a scientifically responsible observation, and it illustrates something important about citizen science: amateur data is most valuable when it is critically examined rather than uncritically celebrated. Loeb’s analysis did not diminish Craggs’s achievement — it contextualised it. The interplay between amateur observation and professional interpretation is precisely how citizen science is supposed to work. Craggs provided the raw visual data; Loeb and others provided the interpretive framework. Together they advanced public understanding.
“The best image was taken by Mitsunori Tsumura on November 22 at 19:25 UTC with a 0.5-meter telescope. The images consistently show a glowing coma with tightly-collimated anti-tail and tail.” — Professor Avi Loeb, Medium, November 2025
Loeb’s analysis also noted that other November 22–24 amateur images — particularly one by Mitsunori Tsumura using a 0.5-meter telescope, and separate captures by Peter Carson Leigh with a 0.315-meter telescope in Spain, and Elena Walter with a 0.432-meter telescope in Chile — consistently showed the expected cometary tail and anti-tail structure, with the tail extending approximately 5 million kilometers and the anti-tail reaching roughly 1 million kilometers from the nucleus.
The story of Paul Craggs and 3I/ATLAS is a vivid illustration of a broader transformation in astronomy that has been accelerating for more than a decade. The barrier between professional and amateur observation has been collapsing steadily, driven by improvements in consumer telescope technology, free access to astronomical processing software, and social media platforms that allow rapid, global dissemination of observational data.
Craggs was far from alone in his pursuit of 3I/ATLAS. The interstellar comet inspired a wave of global amateur activity. Stuart Atkinson of Kendal, Cumbria, UK captured it on November 16 using a Seestar S50 smart telescope — another consumer-grade instrument costing several hundred dollars. Dozens of amateur astronomers from Europe, North America, Asia, and Australia turned their equipment toward the departing visitor as the December 19 Earth-closest-approach date approached.
Meanwhile, live coverage of the closest approach was provided by Gianluca Masi of the Virtual Telescope Project based in Ceccano, Italy — a public astronomy platform that has brought real-time telescope feeds to global audiences for years. The combination of institutional science, semi-professional observatories, and committed backyard astronomers like Craggs created a genuinely collaborative global observation campaign around a single cosmic visitor.
The DWARFLAB Dwarf 3 represents a category of instrument that simply did not exist a decade ago. Sub-$1,000 smart telescopes with automated alignment, onboard image stacking, and smartphone connectivity have placed genuine deep-sky imaging capability in the hands of anyone with a clear patch of sky and a few hours of free time. The fact that Craggs used one to capture a once-in-history interstellar object and generate coverage in international media is not a fluke — it is a demonstration of where the technology has arrived.
Inspired by the response to his 3I/ATLAS images, Craggs launched a GoFundMe campaign titled “Build the Paul Craggs Backyard Observatory” with a goal of $1,600. The project aims to construct a permanent, weather-proof, automated backyard observatory to support deep-sky astrophotography, livestreaming sessions, and educational content — a modest but meaningful step toward making his outreach more consistent and accessible.
Beyond the human drama of its observation, 3I/ATLAS carries genuine scientific value as a messenger from another stellar environment. Every interstellar object detected provides a rare direct sample — in this case purely observational, not physical — of material formed around another star. Comparing its properties to Solar System objects and to the two previous interstellar visitors helps astronomers build a picture of how planetary systems elsewhere form and evolve.
Aster Taylor of the University of Michigan Department of Astronomy and Darryl Seligman of Michigan State University, two of the researchers involved in the initial discovery paper, noted that 3I/ATLAS’s unusual polarimetric signature, dust grain properties, and coma composition all suggest it may have formed under conditions meaningfully different from those that produced Solar System comets. Karen Meech, faculty chair of the Institute for Astronomy at the University of Hawaii and a veteran of interstellar object research going back to ʻOumuamua, helped coordinate the rapid mobilisation of observing resources in the hours after 3I/ATLAS’s interstellar nature was confirmed.
Some researchers have speculated that 3I/ATLAS may be a frozen relic from the early epoch of another star system’s formation — potentially older than our own Sun. If that is correct, then Paul Craggs’s images captured light reflected from material that predates our Solar System entirely — photons that began their journey around another star and ended it on a sensor in a backyard in rural Ontario.
No account of 3I/ATLAS in 2025 would be complete without addressing the significant media noise generated around the possibility that the object might not be natural. Professor Loeb — whose book and public profile have made him the most prominent mainstream scientist willing to seriously consider the possibility of technological artefacts among interstellar objects — discussed 3I/ATLAS extensively in this context throughout the observation window.
It is important to be precise about what Loeb actually claimed versus how his statements were reported. He consistently advocated for comprehensive observational study rather than premature conclusions. His documented position was that the best response to an unusual interstellar object was more data, not more speculation. Headlines attributing to him claims that 3I/ATLAS was definitively alien technology were, without exception, misrepresentations. The broader scientific consensus, as represented by researchers at institutions including the Instituto de Astrofísica de Canarias (IAC), the European Southern Observatory (ESO), and NASA’s Jet Propulsion Laboratory (JPL), was that 3I/ATLAS behaved consistently with a natural, active comet of interstellar origin.
The pattern of “alien spaceship” headlines that circulated alongside legitimate coverage of Craggs’s images is a known feature of interstellar object media cycles — it happened with ʻOumuamua in 2017 and with Borisov in 2019. Readers and researchers alike are well served by treating sensational claims about 3I/ATLAS with the same rigour applied to any other extraordinary assertion: extraordinary evidence required, preliminary observations viewed as preliminary, imaging artifacts examined before conclusions drawn.
By late October 2025, 3I/ATLAS had reached perihelion — its closest approach to the Sun, at a distance of approximately 130 million miles, placing it just outside Mars’s orbit. It passed too close to the Sun for ground-based observation through most of November, before reappearing on the far side and becoming visible again in December as Earth-closest-approach on December 19 approached.
At closest approach, 3I/ATLAS was still 270 million kilometers (168 million miles) from Earth — nearly twice the Earth-Sun distance. It was not visible to the naked eye, with an apparent magnitude hovering around +10, requiring at minimum a modest telescope to observe. The Virtual Telescope Project streamed live coverage of the closest approach, weather permitting, from Ceccano, Italy.
Since December 19, 3I/ATLAS has been moving steadily outward, decelerating as it climbs against the Sun’s gravity, and will eventually reach the same speed at which it entered: approximately 137,000 miles per hour relative to the Sun. By early 2026, it was rapidly fading beyond the reach of most ground-based instruments. It will not return. Whatever star system it originally came from — and we may never know which one — it carries no record of its visit here. Only we do.
There are two ways to read the story of Paul Craggs and 3I/ATLAS. The first is as a feel-good human interest story: ordinary person, consumer equipment, extraordinary result. That reading is accurate as far as it goes, but it undersells what actually happened.
The deeper story is about the structure of modern science and who gets to participate in it. When a $550 smart telescope in a backyard in rural Ontario produces images that circulate in the same international media coverage as observations from the Hubble Space Telescope, the Mars Reconnaissance Orbiter, and the Very Large Telescope — that is not just a charming anecdote. It is evidence of a genuine shift in access to astronomical observation. The tools have democratised. The sky has not changed.
3I/ATLAS itself is gone — or rather, it was always just passing through, indifferent to our instruments and our headlines and our debates about its nature. What remains is the data: thousands of professional and amateur images, spectroscopic measurements, polarimetric observations, X-ray light curves, and the patient work of researchers who will spend years extracting meaning from it all. Among that archive, the images Paul Craggs made with a portable telescope on clear Canadian mornings will hold their place — modest in aperture, significant in what they represent about who astronomy belongs to.
The next interstellar object will come. We do not know when. We do not know from which direction. But the global community of sky-watchers — professional and amateur alike, equipped with anything from a $550 smart telescope to a 10-metre mirror — will be ready to look up.