Our solar system may not be as isolated as we once thought. According to a new study, more than 1 million interstellar objects could be lurking in the outer reaches of our cosmic neighborhood, quietly drifting in the Oort Cloud—the vast, icy shell of comets and asteroids at the edge of the solar system.
The researchers involved in the new study say these aren’t just random space rocks, either. Instead, they argue they’ve traveled light-years, originating from Alpha Centauri, the closest star system to Earth. Until now, though, astronomers have only confirmed two interstellar visitors.
The first interstellar object was ‘Oumuamua, an elongated space rock that some even speculated was an alien spacecraft in 2017, and the comet Borisov in 2019. The latter behaved more like a typical comet but still appeared to have traveled from well beyond our solar system.
However, new simulations suggest that these weren’t isolated objects. Instead, the universe is full of these intriguing cosmic hitchhikers, and many may have liked the Oort Cloud so much that they’ve taken up permanent residence here—at least in a manner of speaking.
See, unlike ‘Oumuamua and Borisov, which zipped through the solar system at breakneck speeds, these newly predicted interstellar objects are stuck. Scientists believe the Sun’s gravity captured them as they passed, stranding them in the Oort Cloud.
And because they’re so far away and don’t emit light, they’re virtually impossible to detect with current telescopes. But the researchers argue that they’re out there, floating silently in the darkness. Plus, since the Alpha Centauri system is believed to be moving toward us, scientists calculate we’ll pick up even more cosmic hitchhikers before it is said and done.
The researchers also calculated how smaller interstellar particles—microscopic grains of alien dust—can travel between star systems. The results, which they’ve published online, suggest that at least ten tiny interstellar particles burn up in Earth’s atmosphere each year, meaning that pieces of Alpha Centauri could be literally raining down on us.
While these interstellar objects are unlikely to pose any danger, their presence suggests that material exchange between star systems is more common than we previously realized. This also raises some exciting questions and possibilities—could interstellar objects carry signs of alien life or materials that shaped early planetary systems?
