Webb image archive
3I/ATLAS Compared to Solar System Comets
Measurements of specific element varieties by the NIRSpec (Near-Infrared Spectrograph) instrument on NASA’s James Webb Space Telescope show how different the interstellar com...
- Date
- Jun 22, 2026
- Observatory
- James Webb Space Telescope
- Credit
- NASA / ESA / CSA / STScI
- Archive ID
- 3i-atlas-compared-to-solar-system-comets
Measurements of specific element varieties by the NIRSpec (Near-Infrared Spectrograph) instrument on NASA’s James Webb Space Telescope show how different the interstellar comet 3I/ATLAS is from comets originating in our own solar system. Researchers used NIRSpec to measure carbon-13, which contains an extra neutron, relative to the more common carbon-12. They also measured the abundance of heavy hydrogen, which is a hydrogen atom with an added neutron.
Webb’s NIRSpec found surprisingly high ratios of heavy hydrogen and heavy carbon, indicating that 3I/ATLAS came from a place very different from our solar system. Researchers say early analysis of these results indicates that 3I/ATLAS was ejected from its origin system billions of years ago.