NASA’s SPHEREx and Webb spot water and CO2 on glowing interstellar Comet 3I/ATLAS beyond the Solar System

NASA’s SPHEREx Mission Spots Rare Interstellar Comet 3I/ATLAS (Image: NASA)

A visitor from beyond the stars has caught NASA’s eye. The interstellar comet 3I/ATLAS, observed between 7 and 15 August, is offering astronomers a rare chance to study material from outside our solar system.

What has NASA discovered with SPHEREx?
NASA announced that its SPHEREx mission recently recorded detailed observations of comet 3I/ATLAS. The spacecraft, designed to map the entire sky in infrared, studied the comet’s size, composition and chemical content. A research note sharing these findings has been released, sparking debate among scientists worldwide.

NASA/SPHEREx

The James Webb Space Telescope and the Hubble Space Telescope have also targeted the icy traveller. Webb is examining the comet’s surface chemistry with its infrared instruments. Hubble is using its sharp optics to refine estimates of the comet’s actual size. Together, these telescopes are helping researchers build one of the clearest profiles yet of a comet that never formed within our own solar system.

On 6 August 2025, the James Webb Space Telescope observed interstellar comet 3I/ATLAS using its Near-Infrared Spectrograph. (Image: NASA/ESA)

Why is comet 3I/ATLAS important?
Comets like 3I/ATLAS act as frozen time capsules. Unlike those from the Kuiper Belt or Oort Cloud, interstellar comets carry chemical fingerprints from distant star systems. These signatures may reveal how planets and stars form elsewhere in the galaxy. Scientists say the comet poses no threat to Earth but offers a rare chance to study raw material from beyond.

What happens next with 3I/ATLAS?
NASA says its fleet of observatories will keep tracking the comet over the coming months. Researchers expect fresh results as data continues to arrive. Each interstellar visitor helps astronomers compare our solar system with others, revealing more about planetary origins.

For now, 3I/ATLAS shines as a glowing reminder that our solar system is not closed, and that travellers from the stars can still pass through our cosmic neighbourhood.