3I/ATLAS in Images: NASA Observes the Interstellar Comet with Its Spacecraft and Telescopes

Interstellar comet 3I/ATLAS continues to captivate both astronomers and the public. After ʻOumuamua in 2017 and 2I/Borisov in 2019, it is only the third interstellar object ever detected in our solar system. A true visitor from another planetary system, it offers a unique scientific opportunity: understanding how comets form… beyond our cosmic neighborhood.

Since its discovery in July 2025 by the ATLAS system, more than a dozen missions have already observed or photographed the comet. Others will have another chance to study it as it races through the planetary region of our solar system at high speed.

By multiplying its vantage points—from Mars, the solar environment, and spacecraft exploring asteroids—NASA gains an unprecedented multi-angle view of an object that comes from another world. These observations make it possible to compare a “foreign” comet with those that originate in our own system and to better understand how planetary systems form elsewhere in the galaxy.

A Rare and Precious Interstellar Visitor

3I/ATLAS was detected in 2025 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) survey. Its hyperbolic orbit—a clear indication that it is not gravitationally bound to the Sun—immediately confirmed its interstellar nature.

Unlike ʻOumuamua, extremely unusual and lacking a visible coma, and unlike Borisov, which behaved more like a “classical” comet, 3I/ATLAS shows unique characteristics that reflect a completely different formation environment.

STEREO, SOHO & PUNCH: Observing the Comet from the Solar Environment

To track the evolution of 3I/ATLAS in the inner solar system, NASA relied on several heliophysics missions dedicated to studying the Sun, the corona, and the solar wind.

Although not designed to observe distant comets, their highly sensitive instruments successfully detected the interstellar visitor as it crossed the heliosphere—a bright, complex, and challenging environment for this type of observation.

Thanks to STEREO-A, SOHO, and PUNCH, NASA obtained a series of unprecedented images showing 3I/ATLAS under different angles and processing techniques, confirming its rapid progression through our solar neighborhood.

STEREO-A: Detecting the Comet in the Heliosphere

The STEREO-A spacecraft, which has monitored solar activity and coronal mass ejections since 2006, observed 3I/ATLAS with its HI-1 (Heliocentric Imager-1) instrument.

To reveal the comet in a very noisy environment, researchers stacked images taken between 11 and 25 September 2025 and applied a colorization method to distinguish the object from heliospheric background features.
At the center, 3I/ATLAS appears as a bright, slightly diffuse orb—an effect of its remarkable velocity of 130,000 mph (209,000 km/h).

STEREO-A Animation: 3I/ATLAS in Motion

The animation created from HI-1 data highlights the comet’s rapid movement across the field of view. The glow from 3I/ATLAS gradually emerges from background noise while the stars remain fixed or appear as streaks depending on the alignment method used.

This dynamic sequence shows the comet literally crossing the heliosphere, confirming its activity and interstellar trajectory.

SOHO: A Faint but Crucial Detection

The ESA/NASA SOHO mission, which has observed the solar corona for more than 25 years, detected 3I/ATLAS on 15–16 October 2025. The image, taken with instruments sensitive to radiation near the Sun, shows a faint brightening in the central region.

Though modest, this detection is significant because it:

• confirms the comet’s presence and brightness near the Sun,

• complements observations from STEREO and PUNCH,

• shows that even an interstellar object can be followed by older but still essential instruments.

PUNCH: A Wide-Field Look at the Comet in the Solar Wind

Using stacked images acquired between 20 September and 3 October 2025, PUNCH provided a wide-field view of the comet, showing:

• a bright point-like nucleus,

• a short, clearly visible tail,

• background stars stretched into trails due to stacking.

PUNCH Animation: Tracking 3I/ATLAS Over 12 Days

These images make it possible to:

• visualize the comet on a large spatial scale,

• track tail formation and direction,

• confirm the object’s fast trajectory through the solar environment.

A Complete View of an Interstellar Passage

By combining data from STEREO-A, SOHO, and PUNCH, NASA obtains a three-dimensional view of 3I/ATLAS as it crosses the heliosphere:

• STEREO-A tracks its movement through a complex environment,

• SOHO confirms its faint but stable brightness,

• PUNCH shows its tail and wide-field context.

Together, these missions highlight the scientific value of this rare visitor and deepen our understanding of how interstellar objects behave when passing through our Sun’s domain.

Solar System Probes: Lucy and Psyche

Thanks to coordinated observations, NASA spacecraft located hundreds of millions of kilometers from the comet contributed valuable data. Two distant missions—Lucy and Psyche—provided unique long-range views from the outer solar system.

Lucy: A Remote but Surprisingly Detailed Observation

These details are impressive considering Lucy is not a comet mission. By measuring the brightness and coma structure, Lucy helps scientists assess the comet’s activity long before its encounter with Mars.

Psyche: Multi-Hour Tracking to Analyze the Coma

Psyche observed 3I/ATLAS on 8–9 September 2025 from a distance of 33 million miles (53 million km), using its multispectral imager to collect four series of images over eight hours.

The stacked data reveal:

• a compact, clearly visible coma,

• a star field used to determine precise positional data,

• brightness variations useful for refining the object’s trajectory.

Lucy provides global structure; Psyche contributes time-series analysis. Combined, they offer a complete long-distance view of the comet’s behavior.

Observing 3I/ATLAS from Mars: A Unique Angle

For the first time, an interstellar object was observed simultaneously from Martian orbit, from the Martian surface, and from interplanetary space—a highlight of NASA’s “Multiple Lenses” campaign.

MAVEN: Ultraviolet Analysis of Interstellar Hydrogen

Using its IUVS ultraviolet spectrograph, MAVEN identified:

• hydrogen emitted by the comet,

• hydrogen from Mars,

• interplanetary hydrogen between the two.

By separating these sources based on velocity, MAVEN isolated the comet’s specific signature—the first detailed UV analysis of an interstellar object from another planet.

Perseverance: A Surface Observation from the Martian Night

On 4 October 2025, the Perseverance rover captured a faint glow of 3I/ATLAS from Jezero Crater using its Mastcam-Z camera—one of the most unexpected and striking images of the entire campaign.

It is valuable because it:

• shows the comet as seen from another planet’s surface,

• enables triangulation with orbital observations,

• demonstrates the extreme sensitivity of Mastcam-Z.

MRO/HiRISE: The Comet Seen from Martian Orbit

By combining observations from MAVEN, Perseverance, and MRO, NASA obtained a three-altitude Martian perspective, allowing:

• precise trajectory refinement,

• comparison of the comet’s brightness from multiple environments,

• study of its interaction with Mars.

3I/ATLAS is not just a curiosity—it is a window into planetary systems beyond our own. Through an unprecedented coordinated effort, NASA has observed it from all angles, using all available spacecraft and telescopes. These images provide a new perspective on a comet from elsewhere and will help deepen our understanding of how planetary systems form across the galaxy.

Source

NASA’s article published on 19 November 2025 is available here. You can find all NASA’s released images of 3I/ATLAS here.