For the reason that interstellar comet 3I/ATLAS was found this previous July — simply the third confirmed object to reach from one other star — astronomers have been carefully following its passage by means of our photo voltaic system.
Because the icy customer brightened on its coast towards the solar, the general public narrative brightened too, with on-line rumors casting it as a attainable alien spacecraft throughout the current 43-day-long authorities shutdown when NASA couldn’t touch upon the item or launch new photos. Final week, with the shutdown over, NASA held a long-awaited briefing during which it shared observations and early evaluation from greater than 20 missions throughout the photo voltaic system, assembling essentially the most full image but of this uncommon customer — and made one level instantly clear: 3I/ATLAS is of pure origin, not an instance of alien expertise.
Discovered on July 1 by the NASA-funded ATLAS telescope in Chile, 3I/ATLAS offers a rare chance to study material forged around another star, scientists say. Early findings suggest the object is carrying chemical clues from a distant, unknown planetary system that’s likely older than our own.
Here are four key things the agency revealed about the interstellar visitor.
1) ‘This object is a comet’
In July, about two weeks after 3I/ATLAS was discovered, a trio of researchers, including Harvard astrophysicist Avi Loeb, posted a non-peer-reviewed preprint arguing that the comet’s traits trace at disguised, probably hostile alien expertise. The declare echoed earlier hypothesis made in regards to the first-known interstellar object, ‘Oumuamua, and shortly gained traction on-line.
It picked up additional momentum after SpaceX CEO Elon Musk steered on a podcast that one thing past gravity may very well be influencing the comet’s movement, and by Kim Kardashian’s viral request on X asking NASA Appearing Administrator Sean Duffy to spill the “tea” on the item.
Throughout final week’s NASA briefing, Kshatriya wasted no time addressing the hypothesis. “This object is a comet,” he mentioned on the outset. “It seems to be and behaves like a comet, and all proof factors to it being a comet.”
Nicky Fox, the affiliate administrator of NASA’s Science Mission Directorate, added that none of NASA’s observations present any technosignatures “or something from it that might lead us to imagine it was something aside from a comet.”
She additionally burdened that scientists are assured 3I/ATLAS poses no threat to Earth, as it’s going to come no nearer than 170 million miles (270 million kilometers) to our planet. It’s going to additionally not come near another planets throughout its passage, together with when it passes the orbit of Jupiter in Spring 2026. The objects in our photo voltaic system, Fox mentioned, “will likely be simply tremendous.”
2) A photo voltaic system-wide watchtower
From the second of its discovery, scientists knew from 3I/ATLAS’ trajectory that it sat on the other aspect of the solar from Earth, making ground-based observations tough. To compensate, NASA convened a coordinated planning session in August, bringing collectively groups from greater than 20 missions to mount a fleet-wide marketing campaign to trace the interstellar comet. Ultimately, dozens of spacecraft from Earth orbit to Mars and beyond worked in concert, each with a different vantage point.
Tom Statler, the lead scientist at NASA for solar system small bodies, likened the effort to watching a baseball game from different seats around the stadium, with both flagship telescopes and smaller spacecraft trying to follow the same fast-moving target.
“Everybody has got a camera and they’re trying to get a picture of the ball,” he said. “Nobody has the perfect view, and everybody has a different camera.”
Mars happened to be on the favorable side of the sun. In early October, NASA’s Mars Reconnaissance Orbiter captured images of 3I/ATLAS as a fuzzy white ball, revealing its dust-and-ice coma, from about 90 million miles (145 million km) away. Around the same time, the MAVEN orbiter detected the comet from 20 million miles (32 million km) through ultraviolet “science wiggles” that picked up signatures of hydrogen gas released as sunlight vaporized the comet’s water ice, said Statler. Combined with data from the Swift telescope and the James Webb Space Telescope (JWST), scientists were able to estimate the comet’s water production rate, a key clue to its formation history.
Other spacecraft offered snapshots from farther out. In September, NASA’s Psyche asteroid mission imaged the comet as a faint blob from 33 million miles (53 million km) away. A week later, the Lucy mission, en route to study Jupiter’s Trojan asteroids, observed the coma and tail from the opposite direction, helping researchers reconstruct the 3D structure of the dust. Even the NASA-European Space Agency SOHO (Solar and Heliospheric Observatory), managed to detect the faint object in mid-October despite expectations that it would be too dim to register, scientists shared during the briefing.
Additional assets contributed further pieces of the puzzle. The Hubble Space Telescope, shortly after its 35th anniversary earlier this year, observed the comet from 277 million miles (446 million km) away, revealing a pear-shaped coma and narrowing the possible size of the nucleus to between 1,400 feet (427 meters) and 3.5 miles (5.6 km). JWST provided the first infrared look at an interstellar object since its launch, detecting an unusually high ratio of carbon dioxide to water ice, well above what’s typical for comets born in our own solar system. That information suggests that 3I/ATLAS’s ices may have been shaped by harsher radiation environments around an older star, scientists said.
“This is a snapshot of where we are very early in the scientific process,” Statler said.
3) A rare window into distant, older star systems
Scientists say that 3I/ATLAS has likely been traveling through interstellar space for a long time. Based on how fast it was moving upon entering the solar system, Statler said the circumstantial evidence points to the comet originating in a very old planetary system, possibly one older than our own.
That “gives me goosebumps to think about, frankly,” he said, noting that 3I/ATLAS may reveal insights into cosmic history that predates the formation of both Earth and the sun.
“It is a new window into the makeups and histories of other solar systems,” he said.
4) Intriguing chemical clues
So far, 3I/ATLAS has behaved exactly as a comet should as it warms near the sun, shedding water and carbon dioxide, but with some intriguing twists. Scientists have detected a higher-than-usual ratio of carbon dioxide to water compared with typical solar system comets, as well as gas unusually rich in nickel relative to iron. Both findings are scientifically compelling and worth further investigation, researchers said.
The dust around the comet also shows slightly atypical properties, suggesting its grain sizes differ from those of local comets. One especially curious behavior was the dust was initially blown toward the sunward side before solar radiation gradually pushed it back, a longer and less common sequence than scientists usually observe in homegrown comets.
“We’re still learning even about what questions we still need to ask,” said Statler. “And this, of course, is the scientific process in action.”
