NASA’s Big Update on Interstellar Comet 3I/ATLAS: 4 Key Findings

Since its discovery in July, the interstellar comet 3I/ATLAS — only the third confirmed object known to have come from beyond our solar system — has been tracked by a fleet of telescopes and spacecraft. After a coordinated campaign involving more than 20 missions, NASA released a set of early findings that together paint the most complete picture yet of this rare visitor.

Quick takeaway

NASA officials say 3I/ATLAS is a natural comet, not an artificial object. Observations from instruments including the James Webb Space Telescope (JWST), Hubble, Mars Reconnaissance Orbiter, MAVEN, Psyche, Lucy and others reveal an object with unusual composition and dust behavior that likely formed in a very old planetary system.

Four key findings

• It’s natural — not alien technology. NASA examined claims and speculation circulating online and concluded the data show no technosignatures. "We very much want to find signs of life in the universe," said a NASA official at the briefing. "But 3I/ATLAS is a comet." Another agency scientist added that none of the observations indicate artificial origin.
• No threat to Earth. 3I/ATLAS will not come closer than about 170 million miles (270 million kilometers) to our planet and will not encounter any planets closely while passing through the solar system, including when it crosses Jupiter's orbit in spring 2026.
• Coordinated, multi-mission observations provided complementary views. Because the comet was on the far side of the Sun from Earth when discovered, ground-based follow-up was limited. NASA mounted a campaign uniting more than 20 missions — from Earth orbit to Mars and beyond — to collect images and spectra from many vantage points. Instruments on Hubble, JWST, Mars Reconnaissance Orbiter, MAVEN, Psyche, Lucy, SOHO, Swift and others contributed data used to estimate nucleus size, water production, gas composition and dust structure.
• Unusual composition and dust properties hint at an old origin. JWST found an unusually high carbon dioxide (CO2)-to-water ratio compared with comets formed in our solar system. Scientists also reported gas that is relatively rich in nickel compared with iron and dust grains with atypical sizes and behavior. For example, dust was initially pushed sunward before radiation pressure later turned it away — a longer and less common sequence than typically seen. Hubble constrained the nucleus size to roughly between 1,400 feet (427 meters) and 3.5 miles (5.6 kilometers).

What this means

Taken together, the observations suggest 3I/ATLAS probably formed in a planetary system older and more heavily irradiated than our own, and that it has been traveling through interstellar space for a long time. "It is a new window into the makeups and histories of other solar systems," said a NASA scientist involved in the campaign.

"We're still learning even about what questions we still need to ask," another mission scientist said. "This is the scientific process in action."

These are early results from an ongoing analysis. Scientists plan additional observations and more detailed modeling to refine estimates of composition, structure and origin as the comet continues its passage through the inner solar system.