International Gemini Observatory/NOIRLab/NSF/AURA/K. Meech (IfA/U. Hawaii)
Image Processing: Jen Miller & Mahdi Zamani (NSF NOIRLab)
Most comets, like the famous Halley’s, orbit through our solar system as icy remnants from its formation about 4.5 billion years ago. But every so often, a truly unusual object appears—something not from around here. These rare visitors are interstellar drifters, either born in distant star systems or wandering alone through the vastness of space.
A Cosmic Wanderer Older Than Earth Itself
On July 1, 2025, Chile’s ATLAS survey telescope detected a curious object in the sky. What it found could be a relic from a time long before our Sun or planets existed. Dubbed 3I/ATLAS, this unexpected discovery has caught astronomers’ attention.
Back when Earth didn’t yet exist—no oceans, no forests, no living creatures—this object may already have been floating through the cosmos. After billions of years of silent travel, it has finally entered our part of the galaxy.
Comet 3I/ATLAS is not just another icy traveler. It’s only the third known object to arrive from interstellar space, bringing with it a rich supply of water ice and a story that stretches back further than we can imagine. Unlike most comets, it likely originated in a completely different region of the Milky Way.
To trace its roots, researchers used the Ōtautahi–Oxford Model, a sophisticated simulation that predicts where such objects might come from based on their trajectories. Their findings suggest that 3I/ATLAS could be over 7.5 billion years old—more than two billion years older than our Sun—making it the most ancient interstellar visitor ever detected.
Originating From the Milky Way’s Thick Disk
This comet’s steep trajectory hints that it came from the Milky Way’s thick disk, a region populated by some of the galaxy’s oldest stars. If it formed near one of these stars, it may contain pristine water ice from the early galaxy.
“We’ve never had such a close look at an object from this part of the galaxy,” said Chris Lintott, co-author of the study and host of The Sky at Night. “There’s a strong chance—about two-thirds—that this comet predates the solar system and has been drifting through space ever since.”
As 3I/ATLAS draws closer to the Sun, it will begin to transform. The rising heat will cause gas and dust to erupt from its surface, forming a glowing coma and tail—like a mist-breathing dragon in the sky.
Early observations suggest that 3I/ATLAS may outshine the previous two interstellar visitors, ‘Oumuamua (2017) and Borisov (2019), both in size and brightness.
Implications for Galactic Chemistry and Planet Formation
If that turns out to be true, it could mean that these ancient cosmic wanderers are more common than we thought—and that they may play a hidden role in spreading the building blocks of stars and planets throughout the galaxy.
“We’re witnessing something remarkable,” said Michele Bannister, a co-author from the University of Canterbury. “3I is already showing activity. As it heats up, the gases we observe will help confirm our models. Some of the world’s largest telescopes are already tracking it—we may uncover even more surprises.”
Just days before this discovery, Oxford astronomer Matthew Hopkins had completed his thesis, likely expecting a break. But that calm didn’t last. As soon as 3I/ATLAS appeared, excited messages filled his inbox: “3I!!!!!!!!!!” He quickly shifted gears to dive back into interstellar data.
Instead of relaxing, Hopkins began applying the Ōtautahi–Oxford Model he had helped develop. For the first time, a real interstellar comet was testing their theoretical predictions in real time—turning academic research into live astronomical exploration.
As for the rest of us on Earth? 3I/ATLAS is expected to become visible in late 2025 or early 2026 with a decent amateur telescope—offering us all a glimpse at an ancient traveler older than the Sun itself.
Read the original article on: New Atlas
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