Best Images of 3I/ATLAS: Every Telescope That Captured the Comet

No astronomical object has ever been observed by as many telescopes — on Earth and in space — as interstellar comet 3I/ATLAS. From its discovery in July 2025 through its fading departure in early 2026, more than a dozen spacecraft and countless ground-based observatories captured this visitor from another star system across every wavelength from X-rays to infrared.

This guide collects the most significant observations into a single visual timeline, from the first faint detection to the dramatic post-perihelion eruptions that continued to surprise scientists months after the comet's closest approach to the Sun.

Discovery: The First Glimpse

The story begins on July 1, 2025, when the NASA-funded ATLAS (Asteroid Terrestrial-impact Last Alert System) telescope at Rio Hurtado, Chile, reported a faint object with cometary appearance to the Minor Planet Center. Within hours, the Zwicky Transient Facility (ZTF) at Palomar found pre-discovery images from June 28-29, extending the orbital arc and revealing a strongly hyperbolic orbit. By July 2, the Minor Planet Center designated it 3I — the third confirmed interstellar object.

Pre-discovery images were later identified as far back as May 22, 2025 in ZTF data and June 25 in ATLAS archives. These early frames showed the comet was already active at distances beyond 4 AU from the Sun — producing a coma of gas and dust while still far from solar heating.

Just two days after the official announcement, ESO's Very Large Telescope captured a time-lapse with its FORS2 instrument on July 3, showing 3I/ATLAS gliding across the star field over 13 minutes. VLT's MUSE spectrograph simultaneously obtained the first spectrum, revealing a red coma with a spectral slope similar to trans-Neptunian objects and the previous interstellar comet 2I/Borisov.

Hubble's Evolving Portrait

Hubble Space Telescope has provided the most scientifically rich visual dataset of 3I/ATLAS, tracking the comet's evolution across seven months.

July 21, 2025 — First look. Hubble's debut image revealed a teardrop-shaped cocoon of dust surrounding the nucleus, with a plume ejected from the Sun-warmed side and the hint of a dust tail. The nucleus was constrained to less than 5.6 km in diameter. Background stars appeared as streaks because Hubble was tracking the comet along its hyperbolic trajectory.

August 20-26, 2025 — Size refined. Follow-up observations narrowed the nucleus estimate to between 440 meters and 5.6 km, with the inner coma appearing fan-shaped and brighter on the Sun-facing side.

November 30, 2025 — Post-perihelion return. After 3I/ATLAS emerged from behind the Sun, Hubble's Wide Field Camera 3 captured a transformed comet. A prominent anti-tail — a dust feature pointing toward the Sun — extended more than 60,000 km (ten times Earth's radius) sunward. Rotational gradient mapping revealed two distinct jets.

December 12-27, 2025 — Wobbling jets. Larson-Sekanina filtering of Hubble data showed a double jet structure whose relative brightness changed between observations. The jets wobbled periodically by +/-20 degrees over a cycle of approximately 7.1 hours — each jet acting like a misaligned lighthouse beam as the nucleus rotated.

January 14-22, 2026 — Triple symmetry. The most dramatic Hubble result: three symmetric mini-jets separated by 120 degrees, surrounding the nucleus with a powerful, tightly collimated anti-tail directed at the Sun. During a rare alignment on January 22 where 3I/ATLAS fell within 0.69 degrees of the Earth-Sun axis, six exposures revealed four jets including the anti-tail.

Post-perihelion data confirmed the nucleus has an effective diameter of 2.6 +/- 0.4 km — roughly 40 times more massive than 2I/Borisov and at least 20,000 times more massive than 1I/'Oumuamua.

Ground-Based Giants

Major ground-based telescopes provided complementary views impossible to achieve from space alone.

Gemini South (August 27, 2025) captured deep multi-color images during a Shadow the Scientists outreach session. The composite used four filters (red, green, blue, ultraviolet) and showed a broad coma with a tail spanning about 1/120th of a degree pointing away from the Sun.

Gemini North (November 26, 2025) revealed one of the most visually striking transformations: 3I/ATLAS now displayed a distinct greenish glow caused by diatomic carbon (C₂) emission. This was a dramatic color change from the red hue seen just three months earlier, indicating significantly increased outgassing activity after perihelion.

The Two-meter Twin Telescope (TTT) at Teide Observatory provided the most extensive early monitoring, observing across 37 nights from July 2 to September 5, 2025. Using Laplacian filtering — which highlights spatial curvature without assuming coma symmetry — the team detected a wobbling jet on 7 nights, measuring a period of 7.74 hours that later matched Hubble's independent measurement.

VLT contributed the first spectroscopic detection of atomic nickel (Ni I) and cyanide (CN) gas at large heliocentric distances, while the Lesedi Telescope in South Africa, SALT, and the Nordic Optical Telescope provided photometric data that pinned down the comet's spin period at 16.16 hours pre-perihelion.

The Amateur Photographers

Amateur observers worldwide contributed observations that ranged from historically significant to genuinely moving.

Satoru Murata (November 16, 2025 — New Mexico) produced one of the most scientifically valuable amateur images. Using a Celestron EdgeHD 800 (0.2-meter aperture), he stacked 24 exposures of 60 seconds each and revealed three separate ionic tail jets and an anti-tail — the first amateur detection of 3I/ATLAS's complex multi-jet morphology. Science journalist Corey S. Powell called the images "marvelous" for capturing such intricate tail structure. Galaxy NGC 4691 appeared in the same field, creating a striking visual juxtaposition of interstellar scales.

Mitsunori Tsumura (November 22, 2025 — Japan) captured what many consider the finest amateur image of 3I/ATLAS. Using a 0.5-meter telescope, the image showed a tail extending 5 million km, an anti-tail reaching 1 million km toward the Sun, a perfectly straight collimated tail, and a coma with striking spherical symmetry. The comet appeared near galaxy NGC 4454 in projection.

Paul Craggs (November 22-24, 2025 — Ontario, Canada) demonstrated the accessibility revolution in astrophotography. His DWARFLAB Dwarf 3 smart telescope — costing approximately $550 — captured images showing a bright, narrow white core surrounded by a smooth blue glow. The photos went viral and were analyzed by Harvard's Avi Loeb, generating media coverage from IBTimes, Zee News, and Mashable.

Osama Fathi (November 29, 2025 — Egypt's Black Desert) created the most iconic landscape astrophotography composition of 3I/ATLAS. Using an astro-modified Nikon Z6 with a William Optics RedCat at 750mm effective focal length, he stacked 120 exposures at 3 AM from one of Earth's darkest locations. The image showed the comet's subtle cyan-green glow from cyanide radical emission framed between desert trees — published in BBC Sky at Night Magazine.

Stuart Atkinson (November 16, 2025 — Cumbria, UK) proved that even a $500 ZWO Seestar S50 could confirm the interstellar visitor. Waking at 4:30 AM to observe from a riverside location with the comet scraping treetops near streetlights and a waning crescent Moon, his detection demonstrated that 3I/ATLAS was accessible to everyday amateur astronomers.

Gianluca Masi / Virtual Telescope Project (November 2025 — Italy) provided the most systematic amateur monitoring, tracking the ion tail's development across a dozen observation nights. His November 11 images showed the ion tail spanning at least 0.7 degrees — growing longer and more defined with each session.

Hidden From Earth: Solar Spacecraft Step In

When 3I/ATLAS disappeared behind the Sun from Earth's perspective in October-November 2025, a constellation of heliophysics spacecraft filled the observation gap.

STEREO-A tracked the comet from September 11 to October 2 using its Heliospheric Imager, producing stacked and colorized frames that kept scientists informed of the comet's behavior during the critical pre-perihelion approach.

SOHO's LASCO coronagraph spotted 3I/ATLAS crossing its field of view from October 15 to 26 — initially thought too faint for detection, detailed stacking revealed the comet brightening at an extraordinary rate proportional to distance-from-Sun to the power of -7.5. Color photometry showed something unexpected: the comet appeared bluer than the Sun near perihelion, a reversal from its pre-perihelion red hue.

GOES-19 CCOR-1 provided additional near-Sun observations from October 9 to November 1, with the comet first identified in the data by citizen scientist Worachate Boonplod.

NASA's PUNCH mission captured 3I/ATLAS from September 20 to October 3 as a bright object near the center of its field, providing a multi-week time-lapse during a period when nearly all other instruments had lost sight of the comet.

Parker Solar Probe made the most sustained observations, using its WISPR camera to capture approximately 10 images per day from October 18 to November 5. The comet was near perihelion, visible heading behind the Sun from Parker's vantage point — a perspective impossible from anywhere near Earth.

A View From Mars

In early October 2025, 3I/ATLAS passed within approximately 30 million km of Mars, offering spacecraft in Mars orbit extraordinarily close views.

MRO's HiRISE camera (October 2, 2025) obtained one of the closest views of any spacecraft — at roughly 30 million km, the comet's coma appeared as a bright blob at approximately 30 km per pixel resolution. While not the sharpest image aesthetically, it represents the highest spatial resolution achieved by any single spacecraft observation.

China's Tianwen-1 orbiter used its HiRIC high-resolution camera on October 3 to capture the comet against a stellar backdrop from a similar distance.

ESA's ExoMars Trace Gas Orbiter and Mars Express both observed during the Mars flyby window (October 1-7), with TGO's CaSSIS camera producing an animated GIF showing the comet's motion. Scientists noted the comet was "10,000 to 100,000 times fainter than our usual target" — demanding creative exposure strategies from instruments designed for planetary surfaces.

MAVEN contributed ultraviolet images from Mars orbit using its IUVS camera over 10 days starting September 27, identifying hydrogen signatures in the coma at a time when the UV view from Earth was blocked.

X-Ray and Infrared: Invisible Light Reveals Hidden Chemistry

Some of the most scientifically significant observations came from telescopes seeing wavelengths invisible to the human eye.

XRISM (November 26-28, 2025) produced the first-ever X-ray image of an interstellar comet. During a 17-hour effective exposure, the Xtend telescope detected a faint X-ray glow extending approximately 400,000 km around the nucleus. The spectrum revealed carbon, nitrogen, and oxygen ions — products of charge exchange interactions where solar wind particles steal electrons from cometary gas molecules. This process is uniquely diagnostic of the comet's composition at scales far larger than visible-light observations can probe.

XMM-Newton (December 3, 2025) followed with approximately 20 hours of observation using its most sensitive X-ray camera, detecting the comet glowing in low-energy X-rays from 282-285 million km. X-ray data is uniquely sensitive to hydrogen and nitrogen gases that are nearly invisible to optical and UV instruments.

JWST's NIRSpec (August 6, 2025) captured the comet's infrared spectrum, revealing it to be CO₂-dominated — with a CO₂/H₂O ratio 4.5 standard deviations above the trend for all known comets. Water ice grains smaller than 1 micrometer, carbon monoxide, and carbonyl sulfide were also detected. Post-perihelion MIRI observations (December 2025) added the first detection of methane (CH₄) in an interstellar comet, at 13.7-27% of the water production rate — a puzzling finding given methane's high volatility.

SPHEREx made two campaigns that bookended perihelion. In August 2025, its 102-band infrared spectrograph revealed a CO₂ coma spanning at least 348,000 km. In December 2025, it caught a dramatic surprise: a post-perihelion eruption with sharp brightness increase, new organic molecules (methanol, cyanide, methane), and evidence of rocky material being ejected. Published in February 2026, these results showed that solar heating was penetrating deeper into the nucleus months after closest approach.

The Comet That Changed Color

One of the most visually distinctive aspects of 3I/ATLAS was its unprecedented color evolution — something no solar system comet has displayed at this scale.

Pre-perihelion (July-September 2025): Red. VLT MUSE spectroscopy measured a spectral slope of 18 +/- 4 percent per 1000 Angstroms — redder than most solar system comets. This reddish hue is characteristic of irradiated organic compounds (tholins) on the surface, similar to D-type asteroids and trans-Neptunian objects. The Astronomy & Astrophysics paper described the color as a "consistently red optical continuum" dominated by dust.

Near perihelion (October 2025): Blue. SOHO LASCO and GOES-19 CCOR-1 color photometry revealed a startling reversal: 3I/ATLAS appeared distinctly bluer than the Sun. This shift indicates that gas emission began contributing substantially to the comet's visible brightness, overwhelming the reddish dust continuum with blue-shifted molecular fluorescence.

Post-perihelion (November 2025): Green. Gemini North's multi-filter observations on November 26 confirmed a vivid greenish glow caused by diatomic carbon (C₂) emission at green wavelengths. This is the same molecule responsible for the green color seen in many solar system comets — but the dramatic shift from red to green over just three months was remarkable.

This three-stage color transformation — red, blue, green — tells the story of progressive heating. As the Sun's energy penetrated deeper into the nucleus, it first released refractory dust (red), then drove intense gas sublimation (blue), and finally reached carbon-rich ices that produced C₂ molecules (green).

Farewell: The Fading Departure

As of February 2026, 3I/ATLAS has faded to magnitude 15 in the constellation Gemini — beyond the reach of all but professional telescopes. The window for amateur observation has closed.

The comet's rotation period tells a final dramatic story. Pre-perihelion measurements showed a leisurely 16.16-hour spin. Post-perihelion Hubble data revealed the nucleus had spun up to approximately 7.1 hours — more than doubling its rotation rate due to outgassing torques during the intense perihelion passage.

The journey ahead is mapped but unobservable for most. 3I/ATLAS will pass closest to Jupiter at just 0.36 AU on March 16, 2026, cross Saturn's orbit in July 2026, reach Uranus's distance in April 2027, and Neptune's in April 2028 — before leaving the solar system permanently, carrying with it the chemical fingerprints of another star's planetary nursery.

In total, at least 15 spacecraft and dozens of ground-based observatories contributed data — making 3I/ATLAS the most thoroughly observed interstellar object in history. The combined dataset spans X-rays to infrared, covers eight months of continuous monitoring, and has already produced more than a dozen peer-reviewed papers. Scientists will be analyzing this treasure trove for years to come.

Track the comet's current position on our Orbit page, find historical milestones on the Timeline, explore the science behind interstellar visitors, and browse community observations on the Media page.