NASA Releases Close-Up Images of Interstellar Comet 3I/ATLAS Ahead of December Flyby

NASA has released new close-up images of 3I/ATLAS, a rare comet that originated from outside our solar system. The pictures come from a coordinated effort by multiple spacecraft and ground-based observatories, offering an unprecedented look at this interstellar visitor.

How the Images Were Captured

3I/ATLAS flew past Mars in early October 2025, at a distance of roughly 18–19 million miles (around 29–30 million kilometers), allowing several orbiters to study it closely. During that flyby, NASA’s Mars Reconnaissance Orbiter used its HiRISE camera to capture detailed images of the comet’s fuzzy nucleus.

Observations also came from the MAVEN satellite, which collected ultraviolet data showing hydrogen emissions in the comet’s coma. In addition, NASA’s Lucy spacecraft photographed the comet with its black-and-white L’LORRI imager while the object was still distant.

Meanwhile, Earth-based and space telescopes added to the understanding. NASA’s James Webb Space Telescope observed the comet using its NIRSpec instrument too. Those observations revealed the comet’s coma was rich in carbon dioxide, and also detected water vapor, carbon monoxide, and dust. Scientists noted that the CO₂-to-H₂O mixing ratio in the coma is among the highest ever observed in any comet. 

What the Images Reveal

The close-up pictures portray 3I/ATLAS as a diffuse, fuzzy object. Rather than a compact solid body, it appears as a white blob surrounded by a cloud of gas and dust. Analysis of the images and spectral data suggests the comet’s nucleus may be anywhere between about 320 meters and 5.6 kilometers in diameter.

Spectroscopic data from the Webb telescope indicate that the coma is unusually rich in carbon dioxide. The presence of hydrogen detected in ultraviolet images points to water vapor escaping and being broken down by sunlight. The images taken by Lucy show that the comet also has a tail, though not as well defined as many solar-system comets.

Why This Matters

3I/ATLAS is only the third confirmed interstellar object known to pass through our solar system, after 1I/’Oumuamua (2017) and 2I/Borisov (2019). Because it comes from another star system, studying its composition gives scientists a rare opportunity to compare its building blocks with those of comets born around the Sun.

The particularly high CO₂ content in its coma suggests that it may have formed in a very different environment from our own comets, or under more intense radiation conditions. (arXiv) This could help researchers understand the diversity of planetary systems and how comets evolve in other star systems.

Scientific and Public Response

Some public speculation had arisen about whether the object might be artificial, but scientists and NASA officials have repeatedly confirmed that 3I/ATLAS is a natural comet, not alien technology. Its behavior and chemical makeup align with naturally occurring comets, though the high CO₂ ratio is unusual.

From a scientific perspective, the observations mark a once-in-a-lifetime opportunity. The comet is making a one-time pass, it will not return. Researchers are coordinating efforts across multiple missions to extract as much data as possible before it drifts out of range.

Looking Ahead

3I/ATLAS is expected to make its closest approach to Earth in mid-December 2025, though it will remain far enough away to pose no risk. Observatories on Earth and in space will continue to monitor it in the coming weeks, aiming to refine measurements of its orbit, size, and chemical composition.

In the long run, studying 3I/ATLAS helps improve understanding of how different star systems form and evolve. By comparing this comet to others from within our own solar system, astronomers hope to learn more about the diversity of cometary bodies across the galaxy — and how they reflect the history of their own origins.