The Hubble Space Telescope image of the interstellar comet 3I/ATLAS on July 21, 2025, when the comet was 277 million miles from Earth in this handout image obtained by Reuters on June 22, 2026. (NASA, ESA, David Jewitt (UCLA); image Processing: Joseph DePasquale (STScI)/Handout via Reuters)
WASHINGTON—Scientists studying the comet 3I/ATLAS have determined that this interstellar visitor is remarkably ancient—formed an estimated 10 to 12 billion years ago in a primordial planetary system—and has a composition unlike anything in our solar system.
An evaluation of the chemical make-up of 3I/ATLAS—only the third interstellar object ever spotted in the solar system—provided guidance about the physical and chemical conditions in the planetary system where it formed, the researchers said.
