Interstellar comet reveals ancient origins
A comet that blazed past the sun last year, known as 3I/Atlas, could be nearly three times older than our solar system, according to a study published in Nature. The comet, which is just the third interstellar visitor ever observed, may be up to 12 billion years old, while the solar system formed about 4.5 billion years ago.
Unique chemical composition detected
Observations from the James Webb Space Telescope and the Alma observatory in Chile revealed that 3I/Atlas has a ratio of chemical elements unlike any solar system body. The comet contains 10 times more deuterium, a type of hydrogen found in heavy water, than local comets. Lead author Martin Cordiner of NASA's Goddard Space Flight Center explained, “That high abundance of heavy water can only really happen, according to our understanding of astrochemistry, in a very cold environment.”
Coldest object observed
The isotopic evidence suggests the comet formed at temperatures as low as -243°C (-405.4°F), making it among the coldest objects ever seen in the solar system. Cordiner noted, “Maybe it’s the oldest object to have been observed in our solar system,” though he acknowledged possible edge-case scenarios.
Mysterious origins in the Milky Way
The comet likely spent billions of years on “vast unimaginable trajectories around our galaxy” after being flung out during the formation of a new planet. Its lack of chemical enrichment suggests it formed relatively close to stars being born, possibly as a relic from “cosmic noon” about 10 billion years ago.
No evidence of alien technology
Earlier speculation by Harvard professor Avi Loeb that 3I/Atlas could be an alien spacecraft was dismissed by NASA. The Search for Extraterrestrial Intelligence Institute (SETI) also found “no evidence of extraterrestrial technology” on the comet.
Future observations
Astronomer Peter Vereš of the International Astronomical Union’s Minor Planet Center called the research “exciting” but noted that the comet is now leaving the solar system and will never return. However, with new facilities like the Vera C. Rubin Observatory in Chile, astronomers expect to spot many more interstellar objects in the coming years. “This is just the beginning of an exciting new field,” Cordiner said.
