WASHINGTON — NASA put out new images Wednesday of 3I/ATLAS, the interstellar comet that’s been making its way through our solar system since astronomers first spotted it back in July. And while they were at it, officials made a point of addressing the rumors that have been swirling online: no, it’s not an alien spacecraft.
“It’s natural to wonder what it is. We love that the world wondered along with us,” said Nicola Fox, associate administrator of NASA’s Science Mission Directorate, speaking at a briefing in Greenbelt, Maryland. She called the comet “our friendly solar system visitor.”
Fox was diplomatic about it, but the message was clear. “We were quick to be able to say, ‘Yup, it definitely behaves like a comet. We certainly haven’t seen any technosignatures or anything from it that would lead us to believe it was anything other than a comet.'”
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Where Did This Thing Come From?
3I/ATLAS was first picked up by an ATLAS telescope in Rio Hurtado, Chile—ATLAS stands for Asteroid Terrestrial-impact Last Alert System, which is basically designed to spot objects that might pose a threat to Earth. What caught astronomers’ attention was its trajectory. This wasn’t something orbiting our sun. It was passing through from somewhere else entirely.
It’s only the third interstellar object astronomers have ever observed visiting our solar system. The first was 1I/’Oumuamua (pronounced oh-MOO-uh-MOO-uh), which showed up in 2017 and sparked its own round of alien speculation. The second was 2I/Borisov, discovered in 2019. Both were comets, and so is this one.
Comets are essentially dirty snowballs—chunks of rock and ice that start releasing gas and dust when they get close to a star and warm up. That’s what creates the distinctive tail and hazy cloud, called a coma, that we associate with comets.
Why the Alien Talk?
So why did people start wondering if 3I/ATLAS might be extraterrestrial technology? One scientist suggested as much, pointing to the comet’s trajectory, composition, and other characteristics as evidence it might not be natural.
NASA Associate Administrator Amit Kshatriya addressed this head-on at the start of Wednesday’s briefing. “I think it’s important that we talk about that. This object is a comet,” he said. “It looks and behaves like a comet. And all evidence points to it being a comet.”
Kshatriya noted that NASA is actively searching for signs of life beyond Earth—pointing to research published in September about a Mars rock sample that might contain traces of ancient microbial life. “We want very much to find signs of life in the universe,” he said. But this isn’t it.
University of Oxford astrophysicist Chris Lintott was even blunter when asked about the alien spacecraft theory. “The idea that 3I/ATLAS could be an alien spacecraft is simply nonsense,” he told Reuters. “There’s nothing about it that suggests such a thing, and you might as well argue that the moon is made of cheese.”
What the Images Show
The new images NASA released—taken by platforms including the Hubble and James Webb space telescopes, along with satellites orbiting Mars—show 3I/ATLAS from a distance. It looks blurry, but you can clearly see the coma and the dust tail trailing behind it as it moves through space. The release of these images had been delayed by the recent U.S. government shutdown.
Tom Statler, NASA’s lead scientist for solar system small bodies, estimated the comet’s nucleus is somewhere between a couple thousand feet to a couple miles in diameter, based on Hubble observations. He said it appears to be “not very far from being round.”
As for where it came from, that’s harder to pin down. NASA scientists believe 3I/ATLAS originated in a solar system older than our own, which formed about 4.5 billion years ago. Its composition is a bit different from comets born in our solar system, which makes sense if it formed somewhere with a different chemical makeup.
Lintott described what astronomers have found so far: “plenty of carbon dioxide and some water, carbon monoxide and other such molecules. We’ve also seen cyanide—normal for a comet—and lots of nickel, which is a bit surprising but not too unprecedented.”
No Danger to Earth
NASA emphasized that 3I/ATLAS poses no threat to Earth. Its closest approach to our planet will come in about a month, but even then it’ll be roughly 170 million miles away. It already made its closest pass by the sun back in October and is now heading back out of the solar system.
For now, astronomers worldwide continue studying it while they can. Interstellar visitors don’t come around often, and each one teaches us something about what’s out there beyond our own cosmic neighborhood. Even if they’re not alien spacecraft.