Meet 3I/ATLAS — The Interstellar Comet Astronomers Are Racing to Study

Meet 3I/ATLAS: A Visitor From Beyond

A comet that originated outside our solar system, designated 3I/ATLAS, is giving astronomers a rare chance to examine material that began its journey billions of years ago in another stellar system. Its interstellar designation (the "i" in 3I) means this object did not form around our Sun — and that makes it exceptionally valuable for understanding how planetary systems form elsewhere.

Why this comet matters

3I/ATLAS is one of only three confirmed interstellar objects detected from Earth so far. It was discovered in 2024 by the ATLAS Survey, a network of telescopes that searches for asteroids and comets that might pose a threat to our planet. Since its discovery, the comet brightened as it approached the Sun and has now reemerged from solar glare, giving researchers a fresh observing window.

"This comet in particular is interesting since it's actually from outside of our solar system," said Qicheng Zhang, a postdoctoral fellow at Lowell Observatory. "The 'i' in 3I stands for interstellar... In this case, it's an interstellar comet because we can actually see it outgassing and producing dust."

Surprising chemistry revealed by JWST

Shortly after discovery, the James Webb Space Telescope (JWST) observed 3I/ATLAS and detected an unusual gas mix: substantially more carbon dioxide relative to water vapor than is typical for comets born in our solar system. That elevated CO₂-to-water ratio could reflect where the object formed or the chemical makeup of its parent star system.

Another explanation is the comet's very high incoming speed. Zhang likened it to "someone throwing a ball down a building instead of just dropping it from rest," meaning the object may have retained volatile ices such as frozen carbon dioxide that slower-moving comets usually lose as they warm.

Watching how it changes

With perihelion (closest approach to the Sun) now behind it, astronomers are closely monitoring how the comet's outgassing and dust production evolve as it recedes. "JWST observations are scheduled for December," Zhang said, adding that follow-up data may give a clearer picture of the comet's composition. Telescopes around the world will track these changes over the coming months to compare this visitor to comets formed in our own system.

What scientists hope to learn

Studying 3I/ATLAS could reveal whether our solar system is chemically unusual or whether similar conditions and building blocks are common across the galaxy. "Is there something special about the solar system that produced life and produced Earth as we know it? Or perhaps that's just something you get with every planetary system," Zhang said.

On speculation and public viewing

Although online chatter has included speculation about engineered objects, scientists urge caution. "There's not really anything about this particular object that screams that it's that peculiar," Zhang said. "We are a long way away from exhausting all explanations that do not involve alien technology."

For amateur astronomers, there is a bonus: 3I/ATLAS is currently at a brightness where observers with small telescopes may be able to spot it. If you decide to look, check current visibility charts from reliable astronomy sources for exact viewing times and coordinates.

Bottom line: 3I/ATLAS is a rare, fast-moving interstellar comet whose unusual carbon-dioxide-rich outgassing is offering scientists a fresh window into how planetary systems beyond our own may form.