No, I don’t mean little grey men in hard candy-shaped ships, I mean natural objects that have origins from outside of our own Solar System—small worlds that formed around a different star. It’s entirely possible that objects can be ejected from a star system and find their way into orbit around another, or even gravitationally “stolen” if stars happen to pass closely enough by each other.
We’ve so far identified a couple of comet-like objects that have passed through our Solar System on hyperbolic trajectories (the first of which was ‘Oumuamua in 2017) but a team of researchers is now suggesting that some of the Centaur asteroids—which orbit the Sun between Saturn and Uranus—as well as a couple of trans-Neptunian objects (TNOs) may actually be “alien” visitors from a different star.
The findings are based on the strangely high inclinations the team’s computer models show these objects once had, back when the Solar System had just formed—far out of the plane of everything else orbiting the Sun. But some scientists remain skeptical of the team’s modeling… to coin a meme, “one does not simply” reverse the motion of the Solar System 4.5 billion years.
So are the Centaurs really aliens? Read more in this May 7, 2020 article by Nola Taylor Redd on Astronomy.com: Astronomers think they’ve found 19 alien objects lurking in the solar system