NASA Discovers Ancient 12-Billion-Year-Old Comet, Older Than the Solar System
An interstellar comet that streaked past the Sun and crossed Earth’s path last year is estimated to be nearly three times older than the solar system. Astronomers say the object is unlike anything previously seen in our cosmic neighbourhood.
Comet 3I/ATLAS is the third interstellar visitor ever observed by humanity, and its unusual brightness provided scientists with an unprecedented opportunity to study something originating from elsewhere in the galaxy. According to a new study published in the journal Nature, 3I/ATLAS could be up to 12 billion years old, whereas our own solar system is thought to have formed only about 4.5 billion years ago.
Lead author Martin Cordiner of NASA’s Goddard Space Flight Center said, ‘It may be the oldest object ever observed in our solar system.’ The new research is based on ratios of chemical elements, called isotopes, detected by NASA’s James Webb Space Telescope and the ALMA observatory in Chile. The study notes that these measurements revealed an elemental composition unlike any other solar system body.
Compared to comets in our solar system, 3I/ATLAS has 10 times more deuterium, a type of hydrogen commonly seen in heavy water. ‘Such a high abundance of heavy water can only really occur, according to our understanding of astrochemistry, in very cold environments,’ Cordiner explained. This suggests the comet is also likely among the coldest objects ever observed in our solar system, with isotopic evidence indicating it formed in an environment with temperatures around minus 243 degrees Celsius.
The origin of comet 3I/ATLAS within the Milky Way remains a mystery, but it is thought to have been ejected during the formation of new planets. After escaping its parent star, the comet wandered the galaxy for billions of years. Curiously, the comet lacks chemical enrichment, indicating it originally formed near newborn stars. Cordiner added that the object could even be a relic from the era known as ‘cosmic noon’, when many stars were forming around 10 billion years ago.
‘The comet is now leaving the solar system and will never return, so future observations will become increasingly difficult,’ said astronomer Peter Veres, who was involved in identifying the comet at the International Astronomical Union’s Minor Planet Center. Nevertheless, astronomers expect to discover more interstellar objects in the coming years, particularly through the new Vera C. Rubin Observatory in Chile.