Interstellar object 3I/ATLAS grows visible tail in live Gemini images. So, it's a comet?
&imwidth=600&imheight=450&format=webp&quality=medium "Interstellar object 3I/ATLAS grows visible tail in live Gemini images. So, it's a comet?")
3I/ATLAS is finally showing a tail. Can we now agree that it is a comet? Photograph: (NSF NOIRLab)
3I/ATLAS is finally growing a tail: New photos of interstellar object 3I/ATLAS show a visible tail spreading in the opposite direction of the Sun. The observations were made during a public educational session. Can we finally agree 3I/ATLAS is an interstellar comet?
New images of the interstellar object 3I/ATLAS are finally showing a visible cometary tail, putting at least some speculation about the visitor to an end. However, several questions remain unanswered about the object that has captivated the imagination of astronomers across the world. Observations made by the Gemini Multi-Object Spectrograph (GMOS) on Gemini South at Cerro Pachón in Chile have revealed a cometary tail and a glowing coma. The discovery was made during a public outreach initiative organised by NSF NOIRLab, in which it connects people with scientists to generate interest in scientific experiments. The session conducted on August 27 revealed that the object was starting to show signs of a comet, with a broad coma, which is a cloud of gas and dust that forms around the comet’s icy nucleus as it gets closer to the Sun.
The tail spans about 1/120th of a degree in the sky in pointing away from the Sun. The new images present a much clearer view of 3I/ATLAS as compared to the other photos taken till now.
The presence of a tail and a coma is likely to put to rest all speculation about 3I/ATLAS and whether it is a comet or a new kind of cosmic object. The new photos also reduce the weight of claims made by Harvard scientist Avi Loeb, who thinks the interstellar object could be an alien spaceship. He had cited the lack of a clear tail as evidence that 3I/ATLAS is not a comet. Loeb also presented a bunch of other details to claim that it was a spacecraft sent by an advanced civilisation. Also Read: Is 3I/ATLAS not alone? Scientist says an invisible ‘probe’ racing ahead of it could strike Mars
Also Read: 3I/ATLAS and its 'intent': Harvard scientist calls on world leaders to prepare for an alien attack
A Q&A session led to the discovery of a tail on 3I/ATLAS
Students from Hawai‘i and La Serena, Chile, remotely joined the Gemini South control room and followed the observations on 3I/ATLAS in real time. The other purpose of the session was to gather data on the comet’s spectrum. This feature of the comet refers to the wavelengths of light that it emits, and can tell about the comet's composition. This information will be valuable to know how the comet changes as it makes its way through the solar system. "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, astronomer at the University of Hawai‘i Institute for Astronomy, and leader of the program. Also Read: 'Wake-up call for humanity’: Scientist wants 3I/ATLAS to be alien spaceship — Here’s why
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Debate over interstellar visitor
Interstellar object 3I/ATLAS was discovered on July 1, 2025, and instantly became an object of fascination among astronomers. They noticed that it was on a strange trajectory, which meant it had come from outer space. 3I/ATLAS is only the third interstellar object to enter our solar system, after ʻOumuamua in 2017 and Comet 2I/Borisov in 2019. It is travelling at a staggering speed of 210,000 km/hour. It will come close to Mars on October 3, and later the Sun, providing the perfect opportunity to study the strange visitor.
