A visitor from beyond our sun's family, the third interstellar object ever witnessed, has carried its own quiet history across the galaxy and now seems to hold a chemical memory older than the solar system itself. Its chemistry, read through the light captured by Webb and ALMA, suggests it was born in deep cold and perhaps near stars still being born, possibly during the era astronomers call cosmic noon, some ten billion years ago. The age is still an estimate, and its scientists hold their certainty loosely, yet the comet offers humanity a rare chance to read a fragment of another part of the
Third Interstellar Visitor 3I/ATLAS May Predate the Solar System by Billions of Years
Older than anything that formed in the solar system
Mark
Twelve billion years old. Why does that number land so hard?
Mimi
Because the solar system is about 4.5 billion years old. This comet would be nearly three times older, and it carries a chemical fingerprint no solar system body matches.
Mark
What's the fingerprint?
Mimi
Ten times more deuterium than solar system comets. That points to formation in extreme cold, around minus 243 degrees Celsius.
Luke
Let me pin down the 12 billion. The study says "up to" 12 billion. That's a ceiling, not a measurement.
Mimi
Right. Seligman, who wasn't involved, says the age is uncertain, though he calls it a safe bet it's older than anything formed here.
Luke
And the lead author himself says "maybe" it's the oldest object observed, and mentions edge-case scenarios that could explain the chemistry differently.
Mark
So what's solid?
Luke
The isotope measurements from JWST and ALMA, and the deuterium excess. The age and the cosmic noon origin are interpretations. Where it came from in the galaxy is unknown.
Mark
And the alien spacecraft talk?
Mimi
NASA dismissed it, and SETI said last month it found no evidence of extraterrestrial technology.
Mark
What's the clock on this?
Mimi
The comet is leaving and won't return, so follow-up gets harder. The hope is Rubin finds more.
Il Polso
- A comet with roughly ten times the deuterium of familiar Solar System comets has unsettled assumptions about where it was born.
- Excitement and speculation about alien technology rippled online, then were pushed back by NASA and a SETI search finding no sign of extraterrestrial machinery.
- Researchers are racing to decode isotope ratios from JWST and ALMA, a measurement that earlier interstellar visitors were too faint to allow.
- The comet is departing the Solar System for good, so follow-up observations will become steadily harder.
- The Vera C. Rubin Observatory is poised to reveal many more interstellar objects, shifting the field from single mysteries to a broader survey.
A visitor from beyond our sun's family, the third interstellar object ever witnessed, has carried its own quiet history across the galaxy and now seems to hold a chemical memory older than the solar system itself. Its chemistry, read through the light captured by Webb and ALMA, suggests it was born in deep cold and perhaps near stars still being born, possibly during the era astronomers call cosmic noon, some ten billion years ago. The age is still an estimate, and its scientists hold their certainty loosely, yet the comet offers humanity a rare chance to read a fragment of another part of the Milky Way. Its departure means this window is already closing, even as the coming decade promises more such travelers.
The comet that swept past the sun last year may be a relic far older than our own neighborhood, and astronomers now say it could be as much as 12 billion years old, nearly three times the age of the solar system. Named 3I/ATLAS, it is only the third interstellar visitor humanity has ever observed, and its arrival first stirred wild online talk of an alien spacecraft. Those claims were set aside when NASA rejected them and a search for extraterrestrial intelligence found no sign of technology aboard.
The real story lies in the comet's chemistry. Using isotope measurements from the James Webb Space Telescope and the ALMA observatory in Chile, a team led by Martin Cordiner of NASA's Goddard Space Flight Center found ten times the deuterium of comets in our own system. Such heavy water, they argue, can only form in extraordinarily cold conditions, near minus 243 degrees Celsius, and the comet also lacks the chemical enrichment expected from older material. Cordiner suggests it may have formed near stars during cosmic noon, roughly ten billion years ago, though he stresses that the age is uncertain and other explanations remain possible.
The finding is considered a first. Earlier interstellar objects, 'Oumuamua and 2I/Borisov, were too faint for such detailed analysis, and 3I/ATLAS's brightness finally made it possible. Outside scientists called the results unprecedented, though the comet is now heading out of the solar system and will never return. Attention is turning to what comes next, as the Vera C. Rubin Observatory is expected to find many more interstellar travelers, and Cordiner calls this only the beginning of a new field.
The comet that swung past the sun last year may be nearly three times older than the solar system itself, astronomers said Monday, and its chemistry looks unlike anything catalogued among our own neighbors. The object is 3I/ATLAS, only the third interstellar visitor humanity has ever observed, and a new study in the journal Nature puts its age at up to 12 billion years. The solar system, by comparison, is believed to have formed about 4.5 billion years ago.
The comet was first spotted in July last year. Its arrival set off excitement online, including speculation from a prominent Harvard researcher, Avi Loeb, that it might be an alien spacecraft. Loeb had earlier made a similar suggestion about 1I/'Oumuamua, the first interstellar object, seen in 2017. NASA rejected the idea for 3I/ATLAS, and last month the Search for Extraterrestrial Intelligence Institute said it had found no evidence of extraterrestrial technology on the comet.
The new work rests on isotope ratios measured by the James Webb Space Telescope and the ALMA observatory in Chile. The study says these measurements reveal an elemental composition unlike any solar system body. Chief among the findings: compared with comets in our solar system, 3I/ATLAS carries ten times more deuterium, a form of hydrogen found in heavy water. Lead author Martin Cordiner of NASA's Goddard Space Flight Center told AFP that, by current understanding of astrochemistry, such a high abundance of heavy water can arise only in a very cold environment.
The isotopic evidence points to formation at minus 243°C (minus 405°F), which would make the comet one of the coldest objects ever seen in our solar system. The researchers also found a strange lack of chemical enrichment, which suggests the comet formed relatively close to stars being born. Cordiner said it could even be a relic of "cosmic noon," a period around 10 billion years ago when many stars were forming.
Where in the Milky Way the comet came from remains unknown. Interstellar objects are thought to form much as solar system comets do, flung out during the violent birth of a new planet. Untethered to any star, 3I/ATLAS probably spent billions of years on what Cordiner called vast, unimaginable trajectories around the galaxy. "Maybe it's the oldest object to have been observed in our solar system," he told AFP, though he added that "edge-case scenarios" could offer other explanations for its unusual composition.
This kind of measurement was not possible before. Neither 'Oumuamua nor 2I/Borisov, spotted in 2019, was bright enough to yield isotopic evidence. 3I/ATLAS's unusual brightness changed that.
Astronomers who studied the comet but were not part of the new research called the results unprecedented. Darryl Seligman of Michigan State University said that until these measurements, such information about an interstellar object was something scientists could only dream about. He cautioned that the age remains uncertain, but called it a safe bet that the comet is older than anything that formed in the solar system. Peter Veres, who helped identify the comet at the International Astronomical Union's Minor Planet Center, called the research exciting, and noted a limit: the comet is leaving the solar system and will never return, so future observations will grow harder.
More targets are expected. Astronomers anticipate spotting many additional interstellar objects in coming years, particularly with the new Vera C. Rubin Observatory in Chile. Cordiner called this "just the beginning of an exciting new field."
Citazioni salienti
Maybe it's the oldest object to have been observed in our solar system.— Martin Cordiner, NASA Goddard, lead study author
The comet is now leaving the solar system and will never return, so future observations will become increasingly difficult.— Peter Veres, Minor Planet Center
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