Our old pal, Comet 3I/ATLAS, is back in the news. The comet we breathlessly covered last year as scientists were mystified by this interstellar traveler, some of whom entertained the idea that it might be some kind of alien artifact. It’s become big enough that, like our modern Hollywood franchises, we’ve run out of stories to tell about its present and future, so now we’ve reverted all the way to its past. A team of researchers from the University of Michigan thinks they figured out where it came from, in essence, providing our coverage of its drift through our solar system with a prequel, its own superhero origin story.

According to a study published in Nature Astronomy, Comet 3I/ATLAS likely formed in an extremely cold, isolated part of the galaxy, outside of our solar system, and a neck of the woods that never quite formed into a fully functioning solar neighborhood like ours. The scientists figured this out after detecting unusually high levels of deuterium in the water it contained. Deuterium is a type of hydrogen molecule that’s heavier than a usual hydrogen molecule. On Earth, it’s used in nuclear weapons. In a comet, it means the clump of dirt, rocks, and ice was formed in extremely cold conditions, far colder than any that shaped our own solar system.

Interstellar Objects Like 3I/ATLAS Are Extremely Rare

3I/ATLAS is only the third confirmed interstellar object ever seen passing through our solar system. The first two were 1I/‘Oumuamua and 2I/Borisov, back in 2017 and 2018, respectively. But 3I/Atlas may be the oldest of the bunch. Estimates have its age somewhere around 11 billion years old, making it twice as old as our sun. That means it formed way before the Earth even existed, back when the galaxy was still a jumbled mess of galaxy ingredients that had yet to be fully mixed.

Using the ALMA observatory in Chile, researchers analyzed the comet as it passed through our neighborhood, reaching speeds of about 137,000 miles per hour. It made its closest pass to Earth in December after swinging by Mars, and it’s now on its way out past Jupiter. It’ll keep going after that, never to return to Earth again.

Comet 3I/Atlas didn’t turn out to be alien tech, and it’s a shame that people hyped it up to be something that extraordinary, so extraordinary that the reality of it could never compete. Which is a shame, because it was extraordinary all on its own without having to add a thick layer of science fiction on top of it. It’s a time capsule from outside our galaxy, capturing a moment in the history of our celestial neighborhood from before our planet even existed. That’s incredible. Aliens didn’t need to be layered on top of that.