Study reveals that interstellar comet 3I/Atlas is the oldest ever recorded and with a unique composition
A new study indicates that the interstellar comet 3I/Atlas is estimated to be between 10 and 12 billion years old, presenting a chemical composition never before observed within the Solar System. These findings were published last Monday (22) by the scientific journal Nature.
Astrochemist and planetary scientist Martin Cordiner, who works at NASA’s Goddard Space Flight Center in Greenbelt, Maryland (United States), and is a co-author of the recent research, stated that 3I/Atlas is possibly the oldest object ever documented to cross our star system.
The research suggests that 3I/Atlas originated in significantly colder environmental conditions, approximately -243 degrees Celsius, contrasting with the formation environment of Earth and other bodies in the Solar System, which emerged about 4.5 billion years ago.
With an estimated diameter of 2.6 kilometers, this celestial object undertook a long journey after being ejected from its home planetary system.
“We have never before observed an object with the characteristics of 3I/Atlas,” said Cordiner.
To analyze the comet’s composition, scientists used the James Webb Space Telescope, measuring the proportions of isotopes, which are variations of chemical elements such as hydrogen and carbon.
Hydrogen isotope data provided important clues about the temperature and radiation levels present at the site of 3I/Atlas formation. Carbon isotope relationships, in turn, revealed details about the interstellar gas cloud that generated the celestial body and its original planetary system.
The water detected in the comet had a content of deuterium, an isotope of hydrogen, approximately 30 times higher than that found in other comets within the Solar System. The proportions of carbon isotopes were also different from those recorded on local celestial bodies and in nearby interstellar clouds and protoplanetary disks.
Cordiner also highlighted that 3I/Atlas probably represents a remnant of the planetary formation process that took place around a different star.
“Analyses carried out with the James Webb Telescope indicate that the environment where 3I/Atlas formed was unique, differing from the Solar System”, explained Cordiner. He added that this location was “probably cooler and less abundant in metals, as well as receiving greater irradiation from UV and cosmic rays.”
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The presence of organic molecules in 3I/Atlas, containing elements such as carbon, hydrogen, nitrogen, oxygen and sulfur, is notable. According to Cordiner, this “demonstrates that, even with formation in a cold and remote environment, the volatile components essential for life as we know it were widely available in that distant protoplanetary disk.”
Analysis of the carbon composition pointed to the formation of 3I/Atlas approximately 12 billion years ago, coinciding with a period of high stellar activity in its original region. This data contextualizes the antiquity of the object, considering that the Universe began with the Big Bang around 13.8 billion years ago, positioning the comet among the first complex celestial bodies to form.
Although scientists believe that the comet originated in the Milky Way, its advanced age does not exclude the possibility of originating from another galaxy.
Cordiner commented: “I assumed that the distances between galaxies were exceedingly large, but a high-speed interstellar object could, in fact, reach our system in just a billion years, from neighboring galaxies like the Magellanic Clouds.”
Comet 3I/Atlas may have been released from its original system through gravitational interactions with other planets, but the hypothesis of a collision is also considered by researchers.
Previously, two other interstellar objects were identified in transit through the Solar System: comets 1I/’Oumuamua, seen in 2017, and 2I/Borisov, discovered in 2019.
Currently, 3I/Atlas is approaching the orbit of Saturn and, according to projections, will cross the orbit of Pluto in 2029, and then leave the outermost region of the Solar System around 2035.
Despite conspiracy theories that link it to alien ships, scientists remain certain that 3I/Atlas is an object of natural origin.
“Although serious scientists are always willing to revise their understanding, we evaluate the evidence for each hypothesis with great rigor,” Cordiner said. He added that, “in this specific case, from the beginning, the evidence clearly indicated the observation of an object with comet-like characteristics, and this conclusion was reinforced by subsequent analyses.”
