In early October, something incredible happened in our Solar System. The third confirmed interstellar object, known as 3I/ATLAS, made a close flyby of Mars. Interstellar objects are space rocks or comets that come from far beyond our Solar System, so spotting one up close is extremely rare.
A Rare Visitor Comes Close to Mars
3I/ATLAS passed only 30 million km from Mars — close enough for several spacecraft orbiting the planet to try capturing images of it. Space agencies from Europe and China quickly released their pictures, but NASA had to wait because of a government shutdown. Now that operations are back to normal, NASA has finally shared the images taken by its missions at Mars, giving scientists and space fans a better look at this mysterious visitor.
The images come from three NASA missions:
- The Mars Reconnaissance Orbiter (MRO)
- The MAVEN orbiter
- The Perseverance rover on the Martian surface
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These pictures reveal the comet’s glowing cloud of dust, its ultraviolet activity, and even faint views from the surface of Mars.
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The Mars Reconnaissance Orbiter (MRO) used its powerful HiRISE camera to take visible-light photos of 3I/ATLAS on October 2. Normally, this camera studies Mars’ surface, but the spacecraft turned itself to face 3I/ATLAS as it flew past. At the time, 3I/ATLAS was about 0.2 astronomical units away, which is still quite far, but close enough for HiRISE to spot it.
The images show 3I/ATLAS as a glowing white ball surrounded by a thick, misty cloud of gas and dust known as a coma. As 3I/ATLAS moved closer to the Sun, its icy core released gas, creating this bright halo. NASA says the coma of 3I/ATLAS reaches about 1,500 km wide, making it much larger than its solid center.
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Studying these pictures may help scientists figure out the size and color of the nucleus of 3I/ATLAS — its solid core of ice and dust. This is especially important because interstellar objects like 3I/ATLAS are extremely rare. Before this, only two were confirmed: 1I/‘Oumuamua in 2017 and 2I/Borisov in 2019.
NASA’s second spacecraft, MAVEN, also observed 3I/ATLAS from September 27 to October 7 using its ultraviolet camera. These images look very different from the visible-light ones. In UV light, 3I/ATLAS appears as a bright dot with a mix of white, blue, and purple shades. This shows how gases around 3I/ATLAS glow when hit by sunlight.
The UV data also helped scientists investigate the chemical makeup of 3I/ATLAS. MAVEN detected different types of hydrogen, including hydrogen released as 3I/ATLAS warmed up and began releasing water vapor. These findings could offer hints about where 3I/ATLAS originally came from before it drifted into our Solar System.
A Faint but Powerful View from the Martian Surface
One of the most surprising images came from the Perseverance rover, which is sitting inside the Jezero Crater on Mars. On October 4, the rover used its Mastcam-Z camera to try spotting the comet from the ground. Because the comet was so faint, Perseverance had to use very long exposures to capture it. This caused the stars in the sky to appear as bright streaks, while the comet showed up as a tiny, blurry smudge marked by crosshairs.
Even though the view is faint, it is still special — it shows an interstellar object seen from the surface of another planet, something that has almost never been done before.
Additional composite images released by NASA show different types of hydrogen detected around Mars at the same time. These include hydrogen from Mars’ own atmosphere, hydrogen drifting through space, and hydrogen coming from the comet itself as it heated up. These details help scientists understand how interstellar comets behave when they pass near the Sun.
Since October, 3I/ATLAS has moved behind the Sun and reappeared on the other side. As it comes back into view, astronomers say it is showing new activity, including becoming brighter and displaying fresh ultraviolet and X-ray behavior. Its color also appears to be changing, which may mean it is shedding new material as it continues its long journey.
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The interstellar comet will make its closest approach to Earth on December 19, 2025. Even then, it will still be far away — almost twice the distance between the Earth and the Sun. NASA confirms it poses no danger to our planet.
For now, the images released from Mars offer a rare glimpse of an object that traveled from another star system, passed close to Mars, and gave scientists around the world valuable data that is not likely to be repeated anytime soon.
