Meet Comet 3I/ATLAS, A Wandering Space Rock That Has Experts Talking

Everything You Need To Know About 3I/ATLAS

A comet from another star system, known as 3I/ATLAS, is giving astronomers a rare chance to study an object that began its journey billions of years ago, far beyond our solar system.

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

That “interstellar” label makes it truly rare. It's one of only three confirmed interstellar objects ever detected from our planet.

3I/ATLAS was discovered in 2024 by the ATLAS Survey, a network of telescopes designed to hunt for asteroids and comets that could pose a threat to Earth. “Since July, it’s been brightening as it’s been approaching the sun,” Zhang said.

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Now that it’s reemerging from the Sun’s glare, astronomers are getting another chance to study it, and early data has already revealed a few surprises.

What Makes 3I/ATLAS So Unusual

Shortly after its discovery, the James Webb Space Telescope (JWST) observed 3I/ATLAS and found that it was “outgassing a somewhat unusual mixture of gases that had a lot more carbon dioxide relative to water vapor than normal solar system comets," Zhang explained.

That finding could tell us something extraordinary about the comet's origins. “It could mean that this object just for some reason has a lot of carbon dioxide relative to water, which could be an indication of maybe where it formed or perhaps just the composition of the star or the planetary system that it came from,” Zhang said.

Alternatively, it might be due to its incredible speed. Unlike local comets that slowly drift through our solar system, this one came racing in. “It's equivalent to someone throwing a ball down a building instead of just dropping it from rest," said Zhang.

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What Astronomers Are Looking for Next

Now that the comet has passed its closest point to the Sun, researchers are watching closely to see how it changes. “JWST observations are scheduled for December,” Zhang said, “and perhaps we’ll get a clearer picture of what the comet is actually made of.”

Over the next couple of months, telescopes around the world will track how the comet’s outgassing (the release of vapor and dust that qualifies something as a "comet") changes as it moves away from the Sun.

The goal: to understand how this visitor compares to comets born in our own solar system, and whether its makeup reveals clues about the environment it came from.

Why 3I/ATLAS Matters

Studying 3I/ATLAS could help scientists understand how other planetary systems form, and how our solar system fits into the bigger picture. "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.”

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And while some people online have speculated about alien technology, Zhang was quick to shut that down. “There’s not really anything about this particular object that screams that it’s that peculiar,” he said. “We are a long way away from exhausting all explanation that do not involve alien technology.”

Here’s the best part: You can try spotting 3I/ATLAS yourself. “This comet is at a brightness where a lot of people can actually go out and see it with small telescopes,” Zhang said.

He added, “See with your eyes that this visitor from a completely different planetary system, perhaps on the other side of the galaxy from billions of years ago, is just briefly making its visit through our solar system."

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