Could comet 3I/ATLAS be alien technology? Controversial Harvard astrophysicist says yes

USA Today

30-07-2025

An interstellar object whizzing through our solar system was widely determined to be a comet. But a trio of researchers led by Avi Loeb recently posed a different idea.
One thing about 3I/ATLAS is for certain: It's definitely not from Earth's solar system.
But what exactly is the intriguing interstellar object discovered speeding through our cosmic neighborhood? Most astrophysicists widely agree that 3I/ATLAS displays all the tell-tale signs of an icy comet.
Now, a trio of researchers led by Avi Loeb, a controversial astrophysicist from Harvard University, are positing a very different theory: What if 3I/ATLAS isn't just some random space rock that incurred upon our solar system by happenstance, but an intelligently controlled alien spacecraft?
Even the authors of the recent research paper posing the wild idea aren't completely sold on it, but – hey – extraterrestrial visitors are always fun to think about.
Black holes: Physicists detect largest-ever merger of 2 black holes equal in size to 240 suns
What is 3I/ATLAS?
A comet known as 3I/ATLAS made news earlier in July when it was confirmed to have originated outside of Earth's solar system, making it just one of three known interstellar objects ever discovered in our cosmic neighborhood.
What's more, the object, which scientists estimate to be more than 12 miles wide, is whizzing at 37 miles per second relative to the sun on a trajectory that on Oct. 30 will bring it within about 130 million miles of Earth, according to NASA.
A telescope in Chile – part of the NASA-funded Asteroid Terrestrial-impact Last Alert System (ATLAS) – was the first to spot what initially looked like an unknown asteroid on a path potentially coming close to Earth's orbit.
The observation was reported to the Minor Planet Center, the official authority for observing and reporting new asteroids, comets and other small bodies in the solar system. The object, eventually confirmed as a comet and named 3I/ATLAS, was later confirmed to have interstellar origins after follow-up observations.
Harvard astrophysicist Avi Loeb suggests 3I/ATLAS is alien tech
But is 3I/ATLAS definitely an icy comet?
A trio of researchers that most prominently includes Avi Loeb, an astrophysicist at Harvard University, recently published a paper speculating about whether the object could be "hostile" alien technology.
Loeb, who is renowned for encouraging astrophysicists to have an open mind about extraterrestrials, is the co-founder of the Galileo Project, a research program at the Harvard-Smithsonian Center for Astrophysics dedicated to the scientific search for extraterrestrials.
The recent paper that Loeb co-authored, uploaded July 16 to the preprint server arXiv, is more a "pedagogical exercise" examining the unusual trajectory of 3I/ATLAS and how fast it is traveling through space than a study meant to offer definitive conclusions. The paper has also, it's important to say, not been peer-reviewed.
Loeb further explained the new paper in a blog post on Medium, writing that it was simply an "interesting exercise in its own right, and is fun to explore."
"This hypothesis proposes that our cosmic neighborhood is dangerous, filled with intelligent civilizations that are hostile and silent to avoid detection by potential predators," Loeb wrote.
However, experts who spoke to science news website LiveScience cast serious doubt on Loeb's sensational theory.
"Any suggestion that it's artificial is nonsense on stilts, and is an insult to the exciting work going on to understand this object," Chris Lintott, an astronomer at the University of Oxford who was part of the team that simulated 3I/ATLAS's galactic origins, told Live Science.
Even Loeb admits that 3I/ATLAS being alien technology is unlikely.
"By far, the most likely outcome will be that 3I/ATLAS is a completely natural interstellar object, probably a comet," he wrote in the blog post.
Loeb previously claimed metallic spheres were extraterrestrial
This is far from the first time that Loeb had theorized that an object in our solar system could be not only interstellar, but an extraterrestrial artifact.
Loeb made headlines in August 2023 when he claimed that remnants of a meteor he and a team recovered in the Pacific Ocean were interstellar in origin.
An unusual meteorite Loeb and his team named IM1 had crashed into Earth's atmosphere in 2014. The researchers then retrieved suspected remnants of the meteor in June 2023 off the coast of Papua New Guinea.
By August, Loeb announced that early analysis suggested the metallic spherules were composed of substance unmatched to any existing alloys in our solar system.
At the time, Loeb did not yet have an answer to the question of whether the metallic spheres were either artificial or natural in origin.
Loeb also theorized that comet Oumuamua was alien spaceship
In 2017, the comet Oumuamua, Hawaiian for 'scout' or 'messenger,' became the first interstellar object ever detected flying through the solar system, puzzling scientists with its strange shape and trajectory.
But Loeb posited that the comet − as long as a football field and thin like a cigar − was able to accelerate as it approached the sun by harnessing its solar power as a "light sail," not unlike the way a ship's sail catches the wind. Because no natural phenomenon would be capable of such space travel, Loeb was essentially suggesting Oumuamua could have been an alien spaceship.
A study in March explained the comet's odd orbit as a simple physical mechanism thought to be common among many icy comets: outgassing of hydrogen as the comet warmed in the sunlight.
The only other time an interstellar object has been spotted traveling through our solar system occurred in 2019 when comet Borisov passed by.
Contributing: Mary Walrath-Holdridge, USA TODAY
Eric Lagatta is the Space Connect reporter for the USA TODAY Network. Reach him at [e-mail]