The interstellar comet 3I/ATLAS is ancient, as NASA estimates that it is over 10 billion years old

The interstellar comet 3I/ATLAS has been identified as one of the oldest known objects to have entered our Solar System, according to recent findings published by NASA scientists. Researchers estimate that this comet formed over 10 billion years ago within a primordial planetary system, making it significantly older than any other known object in our neighborhood. Its chemical composition differs markedly from all comets and celestial bodies found within our Solar System, offering new insights into the conditions present during its formation.

The analysis of 3I/ATLAS's chemical makeup, conducted using data from the James Webb Space Telescope, revealed significant clues about the physical and chemical environments that existed in the planetary system where it originated. This comet, which measures approximately 2.6 kilometers in diameter, is believed to be the oldest known object to have entered our Solar System. According to Martin Cordiner, a planetary scientist and astrochemist at NASA’s Goddard Space Flight Center, and lead author of the study published in the scientific journal *Nature*, the comet's origins date back to a time when the universe was just 13 percent of its current age—around 1.8 billion years after the Big Bang.

Cordiner noted that the comet likely formed in an environment much colder than the one in which Earth and other bodies in our Solar System were created. The temperature at the time of its formation is estimated to have been around -243 degrees Celsius, far below the temperatures associated with the early Solar System. Scientists believe that since its formation, the comet has traveled vast distances through space before arriving in our vicinity.

The researchers measured the ratios of isotopes—different forms of chemical elements such as hydrogen and carbon—observed in the comet using the James Webb Space Telescope. These measurements provided critical information about the temperature and radiation levels in the environment where 3I/ATLAS formed. Additionally, the isotope ratios of carbon offered insights into the composition of the interstellar gas cloud from which both the comet and its planetary system originated.

One notable finding is that the water in the comet contains approximately 30 times more deuterium—a heavy isotope of hydrogen—than comets in our Solar System. Furthermore, the carbon isotope ratios observed in 3I/ATLAS differ from those seen in objects within our Solar System as well as in interstellar clouds or protoplanetary disks surrounding young stars. Cordiner suggests that 3I/ATLAS might be a remnant fragment left behind during the process of planet formation around another star.

According to Cordiner, the observations made with the James Webb telescope indicate that the planetary formation environment in the system of origin for 3I/ATLAS was distinct from our Solar System. It was likely colder, less rich in heavy elements, and more exposed to ultraviolet radiation and cosmic rays.

Despite its distant and cold origin, 3I/ATLAS is rich in organic molecules containing carbon, hydrogen, nitrogen, oxygen, and sulfur. Cordiner states that this richness indicates that volatile elements essential for life, as we know it, were abundant in this distant protoplanetary disk. The carbon composition further suggests that the comet formed up to 12 billion years ago, during a period of intense star formation.

Given that the universe is believed to have begun with the Big Bang roughly 13.8 billion years ago, 3I/ATLAS would originate from a time when the universe was still very young. While scientists believe the comet formed within our galaxy, they cannot rule out the possibility that it may have come from another galaxy entirely due to its immense age.

Cordiner expressed surprise at the possibility of such an ancient object traveling from neighboring galaxies like the Magellanic Clouds, stating that while he initially thought intergalactic distances were too vast, a fast-moving interstellar object could indeed reach us from these nearby galaxies within a billion years. This discovery opens up new questions about the potential for similar ancient objects to exist elsewhere in the cosmos and how they might contribute to our understanding of the early universe and the processes of planetary formation.