Spectroscopic measurements of interstellar comet 3I/ATLAS by JWST during Dec 2025 imply that it may be a preserved fragment of an ancient planetary system formed ~12 billion years ago.
This estimate is based on ~30x higher levels of deuterium in its H2O molecules than solar system comets, and low values of carbon-13 compared to carbon-12 in CO and CO2.
Age of the solar system: ~4.6 billions years
Age of the universe: ~13.8 billion years
https://science.nasa.gov/missions/webb/nasas-webb-finds-clues-to-ancient-distant-origin-of-comet-3i-atlas/
https://www.nature.com/articles/s41586-026-10771-6
1/n
This estimate is based on ~30x higher levels of deuterium in its H2O molecules than solar system comets, and low values of carbon-13 compared to carbon-12 in CO and CO2.
Age of the solar system: ~4.6 billions years
Age of the universe: ~13.8 billion years
https://science.nasa.gov/missions/webb/nasas-webb-finds-clues-to-ancient-distant-origin-of-comet-3i-atlas/
https://www.nature.com/articles/s41586-026-10771-6
1/n
1