Strange Origin of Alien Asteroid Oumuamua Reveals There Are Millions More Like It
If Tabby's Star was the most mysterious star in the galaxy, then alien asteroid Oumuamua is probably the most mysterious rock.
The mysteries are slowly being unraveled, however: We know what it's made of (carbon-rich ice and rock), what it's probably not (an alien spaceship), and now we know where it's probably from.
Oumuamua is probably from the "Pleiades moving group," a collection of young stars that are relatively nearby, astronomer Fabo Feng discovered in a new study.
Feng's observations of Oumuamua have given new insight into how old it is: Based on the knowledge that exposure to solar rays slowly turn objects a reddish color, Oumuamua is probably hundreds of millions of years old, while its relatively slow speed means it hasn't been around long enough to encounter stars, dust clouds, or other heavy-gravity areas that would slingshot it and increase its velocity.
Because Oumuamua is made of a mix of ice and rock, Feng believes its original home was the "middle part" of its original solar system.
Using its speed and trajectory, Feng began sketching a picture of how it was ejected from its home and sent to travel the stars.
"Perhaps the most plausible scenario is that Oumuamua was ejected from a closely separated binary star system made of two stars closely orbiting each other," Feng explains. "Objects orbiting one of the stars in a binary system will be strongly affected by the gravity of the other and so can be more easily ejected from the system than if it had just one star."
Based on his research, Feng believes that about 46 million interstellar objects are actually crossing our solar system every year, though they may be too far away for our telescopes to spot them.
This is a huge discovery—observing more interstellar objects like Oumuamua means we can get an even better picture of how other solar systems form, especially how much debris is usually left after a star is born.
That kind of information can be crucial to astronomers, especially if they're, say, trying to distinguish whether a star is dimming because there's an alien Dyson sphere being built around it, or because stars can have giant dust clouds around them.
We still have some time before Oumuamua leaves our solar system, so there may be more to learn from this weird, cigar-shaped rock.