Astronomers have obtained new images of the mysterious interstellar object 3I/ATLAS that reveal a new feature: the fastest comet ever observed has now grown a tail.
The new observations add to the growing body of evidence that supports 3I/ATLAS’s identity as an interstellar comet, amid speculations that include whether the object could represent a probe or other technological artifact produced by an intelligent alien civilization.
A Tail and a Glowing Coma
The discovery of the comet’s tail was made during analysis of images obtained by the Gemini South telescope, located in the Chilean Andes.
In addition to the comet’s gassy tail, the images also showed 3I/ATLAS’s glowing coma, or halo of dust and gas encircling it. As the comet’s icy nucleus warms as it moves closer to the Sun, material on its surface is baked off, producing the coma and tail—both of which are hallmarks of active comets.
Probing the Chemistry of an Interstellar Visitor
In their recent studies, researchers employed the telescope’s Multi-Object Spectrograph to analyze the wavelengths of light emitted by 3I/ATLAS, which provided details about its chemical composition and how its materials are changing during its passage through the Solar System.
The analysis also clearly showed that the object, which already bore several characteristics commonly associated with comets, now possesses a very comet-like tail.
“We were excited to see the growth of the tail, suggesting a change in the particles from the previous Gemini images, and we got our first glimpse of the chemistry from the spectrum,” said Karen Meech from the University of Hawai‘i Institute for Astronomy, speaking with The Independent.
Meech added that the recent observations offer crucially important data, in addition to providing a “breathtaking” view of the mysterious interstellar object as it nears what is expected to be its closest approach to Earth during its journey through our solar system.
NASA Weighs In on 3I/ATLAS
For several weeks, 3I/ATLAS has garnered attention based on speculations that the object could be more than just a comet.
Responding to such speculations, NASA scientist Tom Statler, the Lead Scientist for Solar System Small Bodies in the Planetary Science Division at NASA’s Washington Headquarters, affirmed that all indications currently show that 3I/ATLAS is indeed merely a comet.
“It has some interesting properties that are a little bit different from our solar system comets, but it behaves like a comet,” Statler recently told The Guardian. “And so the evidence is overwhelmingly pointing to this object being a natural body. It’s a comet.” The Debrief reached out to Statler for additional perspectives on the controversy, but had not received a response as of the time of publication.
A Captivating Interstellar Visitor
Discovered on July 1, 2025, 3I/ATLAS is only the third confirmed interstellar object known to have made its way through our Solar System, following in the wake of a pair of equally unusual space objects, 1I/ʻOumuamua in 2017, and Comet 2I/Borisov in 2019.
Clocking in with an estimated diameter of around 3.5 miles, 3I/ATLAS is large, but poses no threat to Earth, and is expected to make its closest pass on its way past Mars next month before it exits our solar system and resumes its interstellar journey.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.
